It's what I agnostic atheist exmo do with my girlfriend reasonable TBM. If you can love them unconditionally with how they are now, then I say go for it. The ideal, in my opinion, is that she discovers what we all know about the lies the church tells her. The religion rather, and more importantly, the church itself is integral to most mormons' identity. Love the man you are going to marry- warts and all he loves yours as well.
And as an outsider it will be obvious to you what's going on, but here's an awesome breakdown from a couple that flipped from "we go to church every week - we will write a Mormon blog" to resigning over the new policy banning children of gays all over the NY Times this month and something that is upsetting many staunch church members a few days ago. There is no question this is the true church. It certainly isn't easy.
Love the man you are going to marry- warts and all he loves yours as well. So basically we were lies to for years. Do you masturbate, ever. If she expresses interest in converting, be prepared to talk about your beliefs, and help her find ways to learn about and follow them.
So you stay calm, stay pleasant, and try not to let it eat you alive. And of course, when it happens, no one the leaver or the faithful spouse could have predicted it. Edit - I just read through some of your other comments. What can you expect. Women do not get to hold the priesthood and function in an equal role with men. Mormons who marry other Mormons in Mormon temples have a 6. Some great ideas include going on a hike or a walk, having a picnic outside or going to museum. I had some idea of his life at the time of wedding, but this is tough. I've luckily broken down my GF's defenses about the church a little bit.