I'd absolutely break up with someone who converted to any of the abrahamic religions in adulthood. There's a reason the holy texts of those religions are used to justify some of the worst things humanity is capable of, and it's because the god of the abrahamic religions is depicted as explicitly approving of most of them. I'm not out on the streets haranguing anyone but I am also not okay with being in a relationship with someone who decides, as an adult, that that entity is worthy of worship.