Wow... Just... Wow.... Do people really have no lives?
It's a FRIGGIN' GAME! *sigh*
The short answer is "Not a damn thing!" Since You get mostly the same from picking up Liara as a brand new LI in ME3 if ye haven't romanced her at all in the earlier 2...
I guess some people have no real life commitments seeing as they are being so defensive and staying true to a gamecharacter... My guess is that most RL partners wouldn't really like You making such a strong commitment to a made up loveinterest in a game...
Even going as far as namecalling for people who wouldn't stay true to that particular love interest of theirs (a tad sick really imho, getting that infatuated in a animated figure)!!!
Geeesh....
Well I now understand why people think gamers are strange... Glad I'm not THAT type of gamer, I can seperate RL from the games, like so many here seem unable to...
(Awaits the flaming from said folks who will take offense, proving me right)
Keep enjoying the games! I do