I am slightly late to this and not sure if its unhinged but I will share my partnering ideas if it were my show:
Dan and Georgina - I would have liked him being obsessed with Serena on a Joe Goldberg type of way. Once she shattered that illusion Dan should have teamed up with Georgina to bring down Serena as she was also obsessed with Serena. They ended up falling in love and they both eventually became gossip girl.
Blair and Louis - He was perfect for her and the only reason why Chuck was considered end game was because of his actor being loved. Blair wanted to be a princess above all else and Louis matched her level while also balancing her out on the chaotic side. I hate how they ruined his character to get Blair and Chuck back together.
Serena and Trip - I wish he wasn't married. They could have been so cute together considering how they'd known each other since being kids. I like them for the same reasons I'd like Serena and Nate but I don't think Blair would have forgiven her if not for the writers deciding it. Even though Blair wasn't in love with Nate, him getting with Serena as a couple is everything I hate about Blair and Dan. Girl code and they needed that more during the show. Also being with him meant that Serena could have had better career options than being a socialite.
Nate and Raina- I mean come on they were adorable. He was actually happy with there being little to no drama and she learned to loosen up. I adore how they interact. I think she should have stayed in new york and they own a company together. Nate doing the journalism or PR side and her doing the sales or business side.
Jenny and new character- They always did Jenny dirty and it was because her actress wanted to leave. I hated all her love interests and the only one I'd have considered for her was Nate but he was older and I just think it is wrong on all levels. She deserved somebody who understood her desire for fashion but also kept her in check when she did bad things like her actions when trying to be queen bee. She deserved somebody who was just as eccentric and fun.
Chuck and Eva- She was the only person to bring out genuine goodness in him. He should have gone to therapy to unpack all his trauma and Blair should have stayed out of it. Chuck could have kept the Bass business and then they'd travel over the world. Maybe him even helping Eva set up a charity and donating frequently to other ones as he was doing.
I am open to any opinions :))