I don't expect this game to go beyond college, in which case, I wouldn't imagine any of the stories to end "Happily Ever After", he's just having a "fucking" good time.
These girls will all have a special place in the mc's heart, but ultimately, it's just young love (mixed with some old love in the case of Jade, Cathy and Bella).
So yeah, I don't see a long term relationship evolving with Bella. I don't even know what she's thinking with wanting to start dating the mc. Maybe she's doing it for herself, to get over her 3 year slump.
So going back to the idea that the mc probably won't get married straight after college, here's the perfect epilogue: