I found romances in both games to be rushed, and ultimately unfullfilling.
In my opinion, there just isn't nearly enough time for an appropriate, deep romance in a CRPG, unless the game was designed around it so more resources would be allocated to it.
It's also very likely that I get sick of people that profess their love to their virtual GFs, so that likely plays a role.
I preferred the Viconia and Jaheira romances to the romances in both KOTOR games.