Have an aunt who has only ever lived with women. I was always told it was her roommate. Everyone refers to her as a roommate. They BOUGHT THE HOUSE TOGETHER. Have dogs together. Raise the other ones kids together.
When I was like 17, and openly gay, I straight up asked my grandmother if her sister was a lesbian. She said no they're just roommates and got super specific about it. I asked my aunt a couple weeks later when I saw her and she went "Well, yeah. Do I not wear enough flannel?"
His personal universe has just been expanded, but his heart might have always been open to the idea of it. He might not be a homophobe.