DD's boyfriend spends a lot of time at our house. They have been together for a while, and I really like him. I have the impression that his parents are getting quite fond of dd too. She is invited to all their family occasions etc. He has been to a few of ours as well. They're not the type to disappear off up to their rooms as soon as they arrive - they each spend quite a lot of time doing stuff with each other's families.
They're great together and they're both very mature/emotionally intelligent, but they're also both extremely young (only 17), so the chances are very high that they will go their separate ways at some point, especially when they both go off to uni next year. I obviously want to be able to support dd properly, if and when that time comes, without my own feelings being a factor. How on earth do you avoid getting too attached to someone when you inevitably end up spending quite a lot of time with them?