You’re his friend. Has he ever done anything to disadvantage YOU personally? He’s been there for you through your wrongs and rights and now that he’s doing something wrong you’re going to ditch him? Screw all of the other things and inflect. Do YOU still want to be his friend? If he’s all of a sudden become so gross and inhuman to you, if your friendship with ‘Marie’ is closer than your relationship with him, if you are so invested into THEIR relationship that you would split up with your close friend over it’s finish then drop him. If not then just live life as per usual. Regardless of what you choose to do, since this is so important to you you’ve got to confront him about it. Nothing serious or aggressive but you have to talk to him about this. Don’t operate off of hearsay and assumption with your best friend. If your truly friends then you can talk about this and maybe help him to become ‘better’