Compatibility does factor in, but at the same time, I think it can only work if one party or both parties doesn't practice as much.
I know a couple sorta like this, Christian man + Muslim girl, but they steer clear of each others' beliefs and aren't up in each others' grill about their separate religions. Still, neither of them are hyper-religious, either, for if they were they could not be. It tends to be extremely hard for most people to strike that balance.
I think that's what I was pointing out. I should have probably put practicing muslim. It's hard to strike a balance for most people because of religious incompatibility. It simply doesn't work unless they ignore their religious values/customs and I don't think that's being authentic. But each to their own.