There is a young woman in our ward that started bringing a boy to church back when she was 14. Of course they weren't dating back then... But he's been coming to church with their family for 3 years, dating the girl for the last year and a half. He's 19 and planning to get baptized soon. Are they going to get married? Did they know at 14 and 15 that this was the 1 person they wanted to ever date and be with forever? And if they don't get married will that ruin his relationship with the church? What if she doesn't want to marry him but doesn't want him to leave the church? They don't have the luxury of dating other people or even waiting until they have experienced several years of independent living because someone they already like, a lot, is before them and temptations are strong.
We don't want our children to date until they are at college. On the one hand that means we won't be around to screen their companions or whatever. But it also means they will have a lot more years of watching the fallout of teen relationships to give them perspective.
The older I get the more I'm amazed that I didn't marry a bum. I had no clue how to watch out for all sorts of behaviors that crash marriages. Even now I don't know what those behaviors are. I'm pretty malleable though. So if someone interested in being financially irresponsible asked me to marry them, I'd probably just be like "OK, let's get a credit card!" That being said, I'd probably have had fun going into debt...
So I don't think it's a good idea to date or marry a non-member. Sure there are a lot of stories of how a spouse was later converted. Or how people get divorced even when they were married in the temple. But when you marry someone that doesn't already share your priorities in religion, it seems that you're setting yourself up for some pretty big arguments down the road. Also, you deserve to marry someone awesome in the temple. So the temptation to feel like that person is holding you back, rather than both giving their all, is not healthy. You can't marry someone you hope to change. It'd be like buying shoes that don't fit you and hoping that will work out somehow. Maybe you can still wear them, but can you run a marathon in them?
All this being judgmentally said, I know not everyone has a chance to date someone awesome that shares their faith. I just feel sad about this situation of the girl in our ward. It's like an arranged marriage, for all the choice they have, because they made a choice when they were really young.