I think both girls come across as nice people, they just made some mistakes in love (and so did the MC by involving himself in both of them at the same time). This hang up of being "cucked" seems to have distorted a lot of people’s understanding of what went wrong here.
Maya was confused (she’s not normally attracted to boys), sad (her long distant relationship was going south) and inexperienced. Josy was also unhappy due to her long distant relationship failing, as well as feeling that the Maya's stupid, interfering father could be an issue in the relationship for who knows how long anyway. They met the MC, went from friends to something a bit more very quickly, and then suddenly it got complicated. Shit happens, especially when emotions are involved.
When the two girls reunited they had a difficult decision to make, going for a long term "throuple" is fraught with danger, normal relationships fail all the time, three people trying to make it work is very unlikely, and the entire discussion and reasoning in the library was just how scared they were to try something like that and screw it up completely. It's a porn game, so we're all thinking, "Yah! Threesome!" only to be told, sorry bud, but us girls don't think this is going to work. A lot of porn game playing Joes (who don't expect rejection and thought it was about the be payoff time) got their noses seriously out of joint, "how dare you cuck me bitches!"...
If the MC is emotionally mature enough to understand what happen and still be friends, that's admirable. If he's hoping to stick around to maybe rekindle the previous relationship, that could be misguided (since if that happens it'd be on the rebound, kinda where he found both girls in the first place).
But it's a porn game, and if you played your cards right, you got your threesome (or maybe you should have just held out for Mel and Sarah).