Housemate (M20) doesn’t talk to girls when their boyfriends are there.

We used to be great friends at university and then we got a house together. Noticed at the beginning that he became very distant and kind of rude to my other housemates (F21) boyfriend (M20). About 5 months ago I started dating our other housemate (M20) and he’s only just started talking to me but still won’t talk to my boyfriend. We’ve had a few conversations about it but it achieves nothing. He’ll be really friendly to me and my female housemate but as soon as our boyfriends are there he’ll blank everyone. Does anyone know why this would be? He’s friendly to other guys and claims he doesn’t have a crush on either of us. He used to be really friendly with both our boyfriends until we got together and now it’s like they’re rivals. It creates really awkward vibes in the house especially when my boyfriend can hear him being really nice to me.

Tldr; Male housemate has a general tendency to blank his friends boyfriends and won’t be friends with me if my boyfriends there.