Hopefully our MC learns from this, and resolves to speak up immediately next time.
He's shown to grow and progress in his behavior and actions up to this point in his efforts to do better by the two (I guess three with the mom) of them up to this point, so it'd be great to see actual changes as the story moves forward and that we don't have a stasis situation with the MC's behavior.
It's gonna be wild when all three of them finally go public at school with their relationship, though. (because I don't believe they have, unless I've really missed something)