Ah, well, usually you need to lose xD So high stress, high arousal, or high TF (for high TF loss I'll update the game today)
Ah, sorry for a missleading description (and for the long answer). It's less about the animations with your opponents, and more about the consequences of losing. So, if you lose, you are sent to the special event with a big screen, where different stuff can happen.
Different ending animations - well, I'm a bit afraid of doing something non-con with your enemies, so need to think better about how to get an agreement from them. Considering that I see our "combat" system as "dating" system, it shouldn't be very hard. After all, all you do is talking, flirting, kissing, and so on. So ending with something sexual is reasonable and quite consensual.