I'm glad she decided not to give up. I think that, even though the two both fell in love with the same person, that with all the set up for both parties involved, I think this is the best situation so far for both of them.
It wouldn't be satisfying if we saw Manbagi instantly get over Tandano, especially with all the set up to this confrontation, and I think it's very in character for Komi to try and stay friends with both of them, but also to value love like that and not wish to sacrifice it so pointlessly. It's very well-written and in character for this to go this way.
Though ya gotta feel bad for the bi guy who's definitely getting cucked now...