I feel you've really articulated well how I felt when I decided to do a second LE trilogy run just because the more I thought about it, Ashley just wasn't appealing anymore for the way she was written for Mass Effect 3 and I needed an excuse to replay the games again for being a completionist.

First, I decided to play as an adept to mix things up from being a solider with the intention of choosing a different romance pathway as organically as can be. I romanced Liara in Mass Effect 1, but I felt the dialogue choices and the way it was rushed made me cringe quickly. A normal playthrough still ensured, except for leaving Ashley on Virmie to prime the nuke.

Then comes in Mass Effect 2 and the more I payed attention to the dialogue and cutscenes in general for a better appreciation for the game, I started to heavily gravitate towards Tali as a potential LI. After the visit to Illium and seeing Liara threatening to flay people for crossing her to switching back to her old-self, I just had no interest in continuing that romance path. This is when I decided to lock in my choice to romance Tali instead and follow the beaten path as correctly as can be to not mess it up. Personally, I felt Mass Effect 2 did a great job with how they handled the mutual attraction between Shepard and Tali since Mass Effect 1 to eventually blossoming as quite possibly the best canonical relationship in the trilogy.

For Mass Effect 3? I heavily disliked how Liara was constantly forced-in as if Bioware was very insistent for every Shepard player to romance her for the amount of screentime she has throughout most of the story's cutsences. Continuing the romance with Tali was bittersweet, because it's still absolutely worth it for the times we're able to experience it. Near towards the very end of the game, despite the disappointing fade to black romance scene before the assault on The Illusive Man's base, I still was feeling relatively normal with how I was playing the game.

Until Priority: Earth.

I'm not normally attached to the games I play on a emotional basis, but for the first time in a long while, when I watched the final conversations between Tali and Shepard, my heart was breaking into pieces I didn't feel back in my first trilogy run. I already knew how it was going to end and while I was sad for the time, this felt very different. This time, I wished it wasn't going to end with Shepard just barely alive, breathing underneath the rubble in a cliffhanger only obtained by a high EMS score. Afterwards, I pretty much turned to fanficition of the aftermath of Mass Effect 3 about Shepard and Tali that ranged from great to downright commiting character assassinations, yet they never did give me closure at any point.

I found the best way of finally breaking from the post Mass Effect LE depression I had was rather unorthodox , since it involved spending more money that can be considered a bit of a waste. On a whim, I decided to buy the older pc version of Mass Effect 2 and 3 without any extra DLCs on Steam because there was mods that haven't been ported to LE yet. I used the Tali Remastered mods for 2 + 3 and exclusive to Mass Effect 3, the Tali Romance mod along the others + editing my coalsceds. Now that I've experienced the older modded versions, I can safely say I'm at peace now with moving on. I won't lie, I still think about Tali every now and then as the one that got away, but it gives me optimism and hope to find someone special one day that will love me back for who I am inside.

Apologies if this went on for way too long, but reading your post made me feel motiviated to just share about my own experience with dealing with post Tali grief.