OK, I have to comment a bit about Kyo because he actually isn't an asshole this chapter and people seem to have missed Fuyuki's recollection. While Kyo did originally want Fuyuki to stay out, he very quickly relented during the conversation itself and invited Fuyuki to spend the birthday together as in previous years. He then went ahead and took the blame when Eri got upset about Fuyuki not coming because he didn't want Eri to know that FUYUKI was deliberately avoiding them. Kyo is really trying to be the nice guy here at a cost to himself, but he's not really helping. That said, he isn't really at fault since all he really did was to give Fuyuki an excuse to do what she'd wanted to do, then Fuyuki changed her mind, then changed her mind AGAIN when she had a chance to repair their relationship. This time most of the blame is really Fuyuki's.
Also, this is a situation where the girls do love each other deeply but one of them (Eri) is actually straight. It's already very obvious from Eri's original reaction to Fuyuki dating senpai that the thought of making their relationship sexual never crossed her mind. She simply isn't wired that way. She loves Fuyuki romantically but is unable to be attracted to her sexually. This kind of pairing does work IRL, and there are mangas that actually depict this. but Eri simply isn't able to initiate it. The ball is really in Fuyuki's court now, especially since she's already come out to both Eri and Kyo. Her original inhibition was caused by her fear of ERI's reaction if she found out. Well, part of that hurdle's already passed.