Romantic Gestures: Accepting Then Rejecting

One thing that constantly leaves me puzzled in this game is how one moment a Sim is receptive to your character's flirtatious advances and then the next, they're rejecting it.

For example, the other night one of my Sims, April, met a woman at the lounge and they had their first kiss and then a proper one. Last night when April saw her again, she went to kiss her just to be pushed away as though saying "What the hell do you think you're doing?!"

Unless you do the "Ask To Be Girlfriend" command BEFORE they part ways for the night/day, it'll be like the kiss never happened.