17 and 20 are very different

I'd be wondering what interest a grown man has in a young vunerable teenage girl.

Gross. But to be honest he's unlikely to find someone his own age really is he with no job, nowhere of his own and not much going for him?

I started going out with DH when I was 23 and he was 32.

That was acceptable. But I don't know when it would have been unacceptable. When I was 19 and he was 28 maybe? But as I mentioned on another thread, I very happily snogged a 26 year old when I was 19.

17 is too young though because you are not an adult.

That said, I think the fact that he has no job and is into debt, drugs and porn is a much bigger issue than his age.

Yes I think that is concerning creepy older men getting involved with 17 year old school girls isn't great is it?

So he’s gaslighting everyone to believe she’s an adult and not a child?

Whether there’s a difference in behaviour/maturity between 17 and 20 (and there is in my opinion, at 17 I was at school dependent on parents for a home and money and at 20 I was living on the other side of the country at drama school working to support myself) is completely irrelevant because she is not 20. She’s 17.

He sounds like a complete loser at best and a predator at worst. She sounds especially vulnerable considering her health. Nightmare scenario.

Actually, if she’s flagged up as vulnerable at school and he represents a danger to her (drugs, porn etc) is it worth seeking advice from pastoral tutor at school? At this age and especially with a vulnerable child I’m not sure where the line is drawn and it moves into safeguarding territory.

17 and 21 are so different I would raise an eyebrow at that age gap being together. There is so much that happens between 17 and 20. At 17 you could be in your first year of sixth form and at 20-21 you could be in your last/second year of uni. You’ve moved out and had jobs. 17 is an age for most people where they’re still only just figuring themselves out.

27 seems far too old. I’m not sure there’s much you could do about it though, it’s technically legal unless he’s in a position of power over her? Is he in anyway ‘above her’ like a teachers helper or a driving instructor? If so, she’s under 18 and that wouldn’t be legal.

He is unemployed since quite a while, living with mother, does occasional drugs, is in debt and is into watching and sharing porn

^ Who in their right mind would want to start a relationship with this person?! Clearly he's preying on a teenager's naivete, as nobody his own age is interested.

Whether there’s a difference in behaviour/maturity between 17 and 20 (and there is in my opinion, at 17 I was at school dependent on parents for a home and money and at 20 I was living on the other side of the country at drama school working to support myself) is completely irrelevant because she is not 20. She’s 17.

I moved out at 17 and lived with a bloke 10 years older. I still went to school but was self-sufficient financially and this meant I worked long hours at a pub for about £3.25 an hour to pay my way (had worked pretty much full time since 15 so had savings etc). I bought a house of my own at 19 and left him.

Clearly the OP has different concerns, and my situation is likely out of the norm, but that’s not to say it can’t happen positively in some cases.

Age aside, he'd be nowhere near my 17yo vulnerable daughter

At 27, even if he was the perfect gentleman he'd be nowhere near my vulnerable daughter.

Combining the two I'd move heaven & earth to ensure he was nowhere near my 17yo vulnerable daughter.

Probably even if she wasn't 'vulnerable' in any other way than being just 17 too.

Id think he was a total creep. A 27 year old should have no interest in a teenager. I think it’s sick.

If that was my daughter at 17 I would step right in I'm afraid.
My sister did similar, went out with a bloke 12 years older than her at 17. It was not healthy. She made all sorts of wrong decisions that made a fundamental difference to her life as am adult. My parents said not one word.
One of my dds was off down a similar path. I had many Frank discussions with her about it and she made sensible choices.

It's legal, so there's not much you can do. My advice would be to be supportive of her, anything else will mean she is likely to feel you are pushing her away and she will move further towards him.

When he's finished with her, which will be once the fun has gone out of things, she will need your support. It will easier if she feels you have always been supportive than if she thinks you didn't approve of her relationship.

If my son was 27 and went out with a 17 year old I'd be having words. But I started dating his dad on my 17th bday and he was 22, so I'd be being a hypocrite.

When I was 16 I had a relationship with a 25 year old man who was overly keen on the idea that I had only very recently lost my virginity. When I look back on it he was creepy as fuck, but at the time I just felt really grown up and special to be receiving attention from an older man. When I was 17 I had a relationship for several years with a 26 year old. He was a loser with drug problems and no hope of a relationship with an equal, and was very controlling and coercive with me. Again, at the time I felt very adult, having an adult relationship, but in hindsight it was really damaging to my self esteem, and I was too young to know what I was getting in to. My parents were blind to his faults, and actually chastised me when I finally managed to extricate myself from the relationship, by which time he’d done a lot of damage to my self esteem and mental health.
I don’t know what your role is in this girl’s life OP, whether or not you have any influence on her, but I guess it would be good if you can keep an eye on her and perhaps be someone she knows she can talk to.

Sorry I didn't read your update. (I mean, there were 16 posts in the thread... ) Obviously if she's not your daughter there's nothing you can do. If the parents don't care then they don't care.

Back in the day though mine was so at 17 I'd been working full time for over a year, so wasn't a naive school girl.

I think it’s grim personally. DH and I are 28 and I can’t imagine either of us finding a teenager even remotely attractive. They aren’t on our radar at all. I teach 17 year old’s and they aren’t appealing, they’re extremely immature and often a pain in the arse!

10 year age gaps aren’t usually an issue but I think dating a young teenager when you’re in your late 20s is weird.

If you're friends with his mother how on earth does she know his porn watching and sharing habits and why is she sharing that information with you?

It’s the last sentence in your OP that would worry me, more than the age difference.

Nothing wrong with ten years difference, but if you're under 18 it's very weird, and ideally I think you'd be post university by the time you dated some one that much older than you.

He is unemployed since quite a while, living with mother, does occasional drugs, is in debt and is into watching and sharing porn.
What on earth does she see in this loser?

There's not a lot that you can do OP. Teenagers don't like being told what they can or can't do and her parents going nuclear would just make her run into his arms. The important thing is that she must know that she has someone to go to when she sees sense who isn't going to go "I told you so".