I really wanted to get under Tali's Visor, as much I wanted to see what you could possibly do with a Quarian Romance scene, my main interest was in seeing a Quarians face... So I sucked up to her my entire first play through, learning everything I could when we visited the Flotilla, but would you believe it? She got hit by a stray round as she was trying to close the doors on the collector ship and I almost wept.
I completed the game, but did it again, following a guide to make sure I kept everyone... Unforunate that Tali's romance scene is boring as hell and we don't even get to see her face. I almost wish I'd just left it as it was.
I had the same thing happen in ME1. I saved Ashley because I thought the objective she was covering was the most important one (not because I liked her) and let Kaiden die, with no prior knowledge that these were the consequences. I was so distraught that I'd let the racist ***** live and the gentle hero die, I fired up a really old save and worked through the whole story again. So now in my ME2 run-through Kaiden's alive, but to be honest it feels hollow. I'm sure it'd have been more interesting living with the "what ifs" but with a save file, death is only an inconvenience.