Wow, old school here. She might be 18 but she doesn’t get to check in and out. I’d set down my expectations. If she wants/plans to spend most of the time with him then I’d discuss that and how that does/does not mesh with your family plans. I wouldn’t attack him but I would certainly note that not being a bad boy can still make for a bad life. And just visiting you once in a while would not cut it in our family.
My kids have been drip fed and seen family members who have limited interest in working hard. We don’t suggest it’s fine. It’s not. The kids realize the implications for those families. I hope your daughter has similar experiences and can see what marrying someone like that takes you. I hope she doesn’t end up with him. Young love is blind. The problem is, people who are lazy often end up with someone who is hard working to support them. Not what I’d want for any of my kids.