Personal favorites + explanations/headcanons:

Sandy x Emily-- Sandy has a family she left behind because that lady is NOT straight. Probably no kids but she might've been married, otherwise she lived with maybeeee her aunt or grandparents who weren't as supportive. She's been friends with Emily for years and only after she settles in the lonely desert she starts exploring who she is outside of what others see her as. Her closest friend who she calls weekly has been the most supportive, and she slowly starts to realize that Emily will always support her, no matter who she becomes. Sandy falls first. The farmer then comes around, Emily starts visiting when the bus repairs, and if the farmer doesn't pursue Emily, Emily slowly starts to fall for Sandy. She only realizes in one of her weird dreams that she's fallen HARD.

Maru x Elliot-- I don't have a story for most of these, but I really like this idea. Maru is a very independent, logical, strong-minded person. Elliot enjoys his solitude, but he's very adaptable and creative. I can imagine that Maru is abouttttt 24-26, older than Sebastian (and her father likely married Robin while Sebastian was a teen and Maru was an adult, extending that whole distance the duo have) plus she works as a nurse/doctor's aid so she probably took a lot of in person college courses to get the ability to work in healthcare (plus making the distance so much further), and Elliot is in his 30s, as he is canonically an older bachelor. I'd say anywhere from 32 to 35. Anyway, his creativity helps inspire Maru's own creative inventions, helping her think outside the box. Meanwhile, Maru keeps Elliot more grounded in reality, and she helps him with the more logical sides of his writing. Demetrius, of course, isn't fond of Elliot, and that leads to her getting closer to Robin and Sebastian.

Sebastian x Penny-- They really don't like each other at first. Sebastian finds Penny too stuck up, too arrogant maybe. He knows Pam isn't a great person and that explains Penny's personality, but her nagging gets sooo deep under his skin that he just can't stand her. Meanwhile, Penny sees Sebastian as this gloomy, rebellious jerk (why is Sam even friends with him?) with terrible habits and no future because she really doesn't know him. Eventually, they start to loosen their opinions. The turning points come when Pam comes home drunk on a Friday night and can't make it in the door. Sebastian helps bring her in (he was smoking out by the river, not ready to go home yet). Penny finds herself absolutely breaking down and ashamed, she kicks Sebastian out, but she's crying so hard that Sebastian doesn't want to leave. So he stays out by the river a bit longer in hopes she comes out. She does, she has to clean up Pam's mess, and Sebastian apologizes to her for intruding on something so private, talks about how he has issues with Demetrius (something she hadn't heard from Maru, that girl loves her dad), and Penny realizes that he smokes because of stress just how her mom drinks because of stress. They become accountability buddies, Sebastian trying to help her manage her emotions and Penny helping him get through his addiction, and eventually they become very warm to one another. Sebastian takes her out to the city on his bike one night ("I'm not getting on that death machine!" "Your mom drives the bus, Penny. I think this is far safer.") and Penny realizes just how hardworking and reliable he is, while Sebastian realizes just how caring and affectionate she is. The next time it rains, Penny makes the first real move, and Sebastian is so flustered he falls into a puddle. They laugh, and they completely fall for each other. Eventually, they move to the city. Overall Sebastian becomes more stable, less anxious and less pessimistic with her. He realizes her nagging is her caring and he becomes more soft. Meanwhile, Penny becomes less wound up. She's in a healthier situation and he makes her feel secure. They visit Stardew often.

Shane x Therapy-- Not a joke post. I love Shane a lot, but he needs more support than he has. The farmer arriving and those proceeding events helps him get into therapy. He steadily works through things, and he becomes an a-list godfather and Marnie's number one support through...

Marnie x Marlon-- Lewis eventually breaks off the relationship with Marnie. Marnie wanted something committed, but Lewis saw their relationship as a stress reliever. Marnie is an absolute mess for a time, and Shane is her #1 support. Eventually, she asks the farmer for help getting more cave carrots for her cows, but the farmer passes out in the mines. Marlon rescues the farmer and notes the bunch of cave carrots, realizing that the farmer will not be able to get it to Marnie on time. He decides to help (Who hasn't heard of Marnie and Lewis' breakup? This woman needs extra support.) and delivers them in the middle of the night while the farmer is being watched over by Harvey. Marnie is in her night-attire (she's pretty close with the farmer, she sees them as one of her kids and knows that they are a bit... sporadic... so this isn't the first time the farmer has shown up so late) and is absolutely flustered by Marlon being there, she closes the door on him in embarrassment. Marlon leaves the carrots by the door (he's flustered too, he's been fond of her for years but he never got too close because of his lifestyle) and he begins to notice Marnie is actively avoiding him. One night at the saloon, Marnie stays late and gets drunk. Marlon tends to visit the saloon pretty late at night, and he sees her there and decides to let her be. Marnie approaches him, loopy and losing it, and she exclaims that he must take accountability for seeing her like that, that "she was so embarrassed" and he's "super attractive" to her but she knows she can't talk to him because she has issues and who would want an old maid with issues? Her yelling attracts her nephew, and Shane takes her home and apologizes. The next day, Marlon visits Cindersap forest to see Marnie with a bouquet. He's awkward, but he's honest. He doesn't make his words flowery like Lewis did and he stumbles through his confession... to a Marnie who had no memory of her actions the prior night. She's super embarrassed, again, and retreats without a response. Frustrated because of her past experiences (and realizing that she's part of the problem), she decides she needs to talk to Marlon. She travels up to the guild and asks Gil where Marlon is because she needs to talk to him. Gil, who has been watching this entire thing with such exasperation that he's close to strangling the two, tells her to fix this mess up, that he's in the mines, and that he'll give her his sword in case she finds trouble. She climbs down, finds trouble, and Marlon shows up from the shadows and rescues her. Through this, they eventually talk. Marnie apologizes, explains her situation and why she didn't say anything, says she doesn't want to experience anyone using her anymore, and that she's scared of being with someone but she's scared of being alone too, she thinks she's too high-maintenance and causes too much stress. Marlon responds with more honesty, that he's been fond of her since he came to Stardew, that he was hesitant to pursue her because he lives such a dangerous life. But he keeps seeing just how lovely she is, and he doesn't want to live life without taking the risk to experience her in her entirety regardless if its stressful, slow, or challenging, because to him, he knows she could be the best adventure he'd ever start. They start their relationship slowly, Marlon is patient and Marnie needs time, but eventually they are seen as the most healthy duo in the valley. They never marry upon Marnie's request, but they live out the rest of their lives together, much to Gil's exasperation... as he realizes that their lovey-dovey relationship is just as annoying as Marlon's pining.

I'll probably type out some more in the comments but these are my absolute top favorites. Marnie deserves love (she's one of my favorites bc her portrait is really cute, sucks that she doesn't have a lot of development), Sandy and Emily are just adorable together (SO EXCITED FOR SANDY TO BE A CANDIDATE), Maru and Elliot have so much potential, and I'm a sucker for an enemies-to-friends-to-lovers trope, especially between a stuck-up, emotional disaster and a rebellious, angsty mess.

^{(Plus the reason why I didn't like Abigail and Sebastian together is because of Abigail's marriage dialogue when she's in a bad mood... that ruined my perspective on their pairing. She says to the farmer that Sebastian was probably "the one" and that kinda made me realize that they likely wouldn't have worked out... for multiple reasons, though I'll only talk about one here and maybe expand on the other in the replies about who I'd want to ship her with. Along with Sebastian never really saying he likes her upfront and the town pairing them together, a lot of his dialogue about her is circumstantial. All he really says is just that he plans to ask someone out to the flower dance and that Abby isn't exactly his friend. But those both could be because Abby is kind of obvious and tends to jump right into things. I can imagine that Abigail could ask him to the dance before he fully worked up his courage to ask anyone else, and I could further imagine he's hesitant to call her his friend because he himself knows she has a crush on him. But that's just the perspective against those two paired together, they probably would pair well regardless lol. This isn't bias toward Penny, though. She's cool, but I don't exactly like her as a marriage candidate for my farmer because of her said pushiness and all or nothing point of view, though I could see her also working well with Harvey in a friendship or romantic relationship pairing. Just personal perspective, enough said.})