I’m an FFB who married a girl whose family (not frum) chose to send her to only frum schools. This was all fine and dandy until they realized that our “lifestyle” didn’t exactly mesh with theirs, ie, real kashrus not just kosher style, shabbos the whole day not just until the evening but it especially came out when we had our kids and sent them to schools “more frum” than they would have chosen. We’ve all come to a place where it’s now quite comfortable, each respecting the others place and not imposing on one another.
But I think the issues that people face in this area are more indicative of the people involved and not the issue. If the religious thing wasn’t the issue, it would be something else. It’s sometimes hard for parents to watch their children make decisions they don’t necessarily agree with, be it religious, college vs. yeshiva, what career they choose or not, where they live, and in some families how they dress their kids. When looking for your life partner, look for someone that has a “yichus” of good people, regardless of their religious affiliation. A good person is a good person, I don’t think there’s any correlation to whether you’re a BT or FFB. Character counts!