@RetiredDad
Ok. You've had some harsh responses on here. They're deserved, but I can imagine they are hard to receive.
This is my experience (and sorry, its gonna be long!)
I've been both where your daughter is and where you are now with a son just entering his third year at university.
My dad was a police officer and I think that, sometimes, he forgot that he was my dad and not my Custody Officer. I recognise a lot of what you say from what he also said. I had a pretty miserable time growing up!
You want to know why your daughter didn't talk to you about leaving college? Well, you talk a lot about wanting her to "listen" to you when, as another poster rightly pointed out, you mean obey. How well do you 'listen' to her? What sort of audience would she have had if she had discussed her plans to leave college with you? I didn't tell my dad when I dropped out of university the first time round because I knew how the conversation would have gone. He didn't listen to me. I was entirely self funded so slightly different in that respect but even so... why talk to someone who doesnt listen to you?
I've never 'advised' my son (ie told him what to do), I've given him my experience but he has always been free to make his own decisions. My parents, on the other hand, lay down the law (much as you are doing) and, as a result, I was still being told I was being "naughty" when I was 27 and a mother myself, simply for not making the same choices they'd have made in all manner of things.
The only house rules i have are about general respect and living in a house with other people (pulling weight with chores etc). He's never had a 'curfew' beyond letting me know if he'd be out past midnight. Which he rarely was because we had established mutual respect by then. And he understood it.
I can understand you not wanting a stream of one night stands to be brought back to your home but a boyfriend? Again, my son was told no ONS etc but an established girlfriend? Why not? Sex doesn't only happen in bed at night - they were having sex anyway and you are not the custodian of your daughter's body (which is where these ideas about boyfriends not stopping over comes from) why is sharing a bed in your house such a problem?
As such, my son has lived at home throughout his degree. He had a girlfriend of 2 years who did stop over and was, in the main, a lovely girl. Perfect? No. But she was his choice and I respected him for it.
There is nothing he doesn't talk to me about (some of it, I'd probably rather not know!!) but I don't want him to ever feel that I am the enemy or someone he has to manage. Has he made mistakes? Of course! Has he chosen routes I could see were disastrous before he took them? Once or twice. But I've always been there to support (not literally pick up the pieces) when he's needed me and I always will be.
You seem to have quite an authoritarian approach to parenting and one that your wife doesn't share.
Your daughter is an adult so she is free to make her own decisions, but she is also a young adult who will still come to you for 'advice' but still won't always get it right. Some of her decisions may be impacted by the fact that a) she doesn't feel you are approachable/your 'advice' is more of a dictat and b) she is trying harder than she should be to prove to you that she is an adult.
I was expected to behave and decision make like a responsible experienced adult, whilst simultaneously being expected to be a child and do as I was told. It's an impossible position to be in because, at that age, you are neither and it's impossible to be both. And the expectations of me changed overnight when I turned 18 yet I had none of the transitional support i needed and the groundwork hadn't been laid.
She still needs parenting and your GUIDANCE but this needs to be done with love and respect. If I've learnt anything, it's that being the parent of a late teen/early 20s is a very different game to parenting a child! She doesn't need your authority she needs your love and emotional support.
Lay off the authority a bit and listen.