The importance of modesty. We visit when he has a rotation that gives him weekends off, and compromise sleep and fun. And most of those end up with both people losing their faith or a divorce.
However, if you are a Catholic guy dating a Mormon girl, then remember that her parents may be averse to it. Even after that, the Church discourages youth from entering serious relationships before they are considering marriage. She might want to follow the 'virgin until marriage' part, or she may personally decide to forego following that in secret.
Soon you'll feel better, because you're not alone. JS married a girl her age when he was 37, after having told her that he had been threatened by an angel with a flaming sword and promising her entire family salvation if she consentedI decided to read the ces letter. I've never understood that bit of the LDS culture. I'm sorry you may be hearing a lot of negativity from us. Anyways, good luck, I hope it works out. If we can say them together, great; if not.
If you like her, and I'm assuming you do, I would suggest you continue the relationship and see how things pan out. Or the links, in that first vision one. I knew a woman who married a man who converted to the church and she spent the rest of their married life telling him he was not good enough. Men search the world for women that they can stand to be around with long-term. If you were the one who did the asking, it is simply chivalrous and gentlemanly for you to pay for dinner, the movie, or whatever else you do. It may not seem like a big deal now, but eventually it will probably surface that at best, the church impacts and influences her behavior in almost every area, at worst, it dictates it.