It happens this way to all of us.
I can give you some advice on what NOT to do, from past experience:
1) It's OK to let her know you miss her, but don't let her feel life is passing you by while you wait for her to call.
2) Don't pile on the guilt when she DOES call - be glad to hear her voice and enjoy her talking to you, but don't lean on her too hard.
3) Keep the welcome mat there, always, but when she comes home make sure she does her own washing. You want to know she's visiting because she wants to see you, not because she's got a load of washing. on the other hand, if she's got some tricky stains, show her how it's done...
4) You now have to stop treating her as your child, and more like your adult friend. Yes, she's still a child until she's 25 (brain maturity thing) but she won't see it that way.
5) Even if you don't like him, make her boyfriend welcome. If you know they are sleeping together, then do not separate them under your roof. What does it achieve, apart from alienation? I now have adult kids and we had to make the same decisions. Last week a lady from church asked after my kids. I told her that BF2 had moved in with us; she was a bit surprised that the little girl she used to babysit is now an adult. She asked where we'd put BF2 - I told her we'd added an extension some years ago and he was out there. Somehow I also mentioned that easy child 2/difficult child 2 is out there with him. She said, "How do you feel about that?"
I explained to her that you can only stand guard at the daughter's bedroom door for so long, then you have to go get some sleep. If the kids are determined to sleep together, they'll do it anywhere. Far better to know where they are and to hope that we've had enough input into their common sense for them to at least take precautions.
Something you CAN do - set up a regular contact arrangement. mother in law has an arrangement with her adult daughter on the other side of the country - at 7 pm every Friday, they take turns telephoning each other for a chat. It's a weekly appointment. One week mother in law rings, the next it's her daughter. And daughter (sister in law) is almost 50, she's been doing this for years.
When I left home (I was 17, living alone in the city) I had to ring my father midweek every week, and come home every weekend. Then I got caught up in university drama revue and they rehearsed on weekends close to performance dates. So I stopped coming home so regularly. However, I WAS home for holidays. Something I noticed - once you move out, you're never really home, ever again, where your parents live. I could be back for the holidays and go to a drawer to get out a shirt or jeans, and find my mother was also using the emptier drawers for her craft work, or her spare clothes. My sister's little ones often slept in my (now empty) bed, so I'd often find a soft toy in my (former) underwear drawer. Meanwhile, although I enjoyed being home and visiting familiar places, a part of me now belonged in the city. I could talk with my mother about my new friends, about the things we did and the jokes we told, but it was too different a world. I was now different and had moved on.
Family is still important to me, but my parents are long gone. My siblings have organised a family reunion, mostly for the next generation (or two) which should be interesting. But many of us have gone in such different directions it's difficult to know what to talk about sometimes. We're politically and morally polarised.
And this is what happens. It is how it should be. It should be the aim of every parent to raise their children to be happy, independent and productive.
A parent's influence begins to wane when they reach their teens. By the time they're in their late teens, they're making almost all their moral decisions by themselves. All we can do is the best we can, while we can. Then you sit back and watch them fly, and hope they remember you sometimes and drop in for a visit.
Mind you, it's perfectly OK to call them yourself sometimes just for a chat. Always ask, "Is this a good time for a natter? If not, when should I call you back?" And keep the conversation light, talk about friends, ask how she's going, how she's enjoying life there, be glad for her if she is, commiserate and support if she is not. Ask her to choose a date to come home one weekend for a visit, when it's convenient, and to give you enough warning so you can organise her favourite meal. And bring boyfriend too. He is a big part of her life now, so if you've done your job right, she should have made a choice with some wisdom in it. To welcome him is to value her judgement and choices. Treat him also, as a reasoning adult. here's hoping he doesn't rub you the wrong way too much!
And keep it light, keep things humorous and warm. Show by example.
A last thought - husband & I are a good couple together. At least, WE think so. I know a few people at church find it offensive how we hold hands a lot, hug a lot and are affectionate with each other (no, we're not all over each other!). But this is not always the experience of the partners our kids bring home. difficult child 1's girlfriend comes from a very unhappy home. Her parents rarely speak to each other. girlfriend has been of the belief that long-term relationships are fiction, that all relationships will eventually fizzle and fail, and determined that before that happens to her, she will leave rather than inflict pain on her partner. She also was determined that she would never inflict conflict like that on kids, so she would never have kids.
Then we welcomed her into our home. She has seen us together, seen how we 'handle' our kids and how we communicate with each other, and is slowly changing her mind. She can see the parallels between husband and difficult child 1, and I think is slowly realising that she at last has a chance at something very special, with a bloke who has his faults but is always going to be loving and loyal.
easy child 2/difficult child 2 says BF2 has said the same thing. His parents are happier than girlfriend's, but it's still a highly volatile relationship with a lot of shouting. Sometimes his parents communicate with each other through him, even though he's living with us now. very sad - but he is seeing how husband & I work as a team and is taking notes, according to our daughter.
So never doubt the impact you can have, just with your example.
husband & I are not perfect. But we try. I think that counts for a lot with the kids.
Marg