Yeah, that can go one of more than a couple of ways I am thinking. Most obvious is fireworks, Jill freaks and Bella offers to bail.
Next Jill freaks, offers to bail
Next Jill freaks, Bella freaks and MC freaks, with a cliff hanger
Next is Jill freaks, Bella tells her to chill and MC says how about both of you- they both dump him
Next as previous but they accept the thruple.
Next, Jill doesn't freak, but she and Bella force MC to choose.
Next is Jill doesn't freak, asks Bella to thruple with MC and they all accept.
Last is Jill doesn't freak, asks Bella and MC to thruple and Bella says no, makes MC choose.