Seeing as I married a Christian twenty-something years ago, I might be expected to say "it's not really relevant, but I'd be quite happy dating a theist".. but, it's getting relevant again as we separated in January.
As I feel now, I would be far happier dating an atheist.. part of it is me: I've become far less tolerant of religious silliness, and there is a lot of it. Even though my wife (we haven't divorced yet) is not particularly religious, there were still times I had to bite my tongue to maintain marital harmony. We basically got through decades of marriage avoiding god & religion as topics. I'm not going to do that again.
sorry to hear of your marital troubles.
in truth, she probably wants to talk about her religion with a like minded person, and who better than her spouse? that is the difficulty, with this type of thing. it isn't to be exclusionary,but rather it prevents future fall out and pain, if you just realize up front that dating a theist isn't going to work in the long run.