AIBU to think this is too big an age gap for a 17-year-old girl?

[Covywovy]

Hi my 17-year-old niece is at college and has started seeing a 25-year-old man.
He seems nice but lazy and still at home.
Despite his apparent politeness, I think he's creepy and dodgy.
Now I do NOT think he's a paedophile or anything. I must be absolutely clear about that but still it seems off to me.

Dh is ten years older than me but I met him when I was 30 and a grown woman so hardly the same thing.

I mean wtf is a 25-year-old man doing with a young girl like this? Yeah, I can probably guess.
AIBU?

@Orangebug

Half your age plus 7? So as a 47yo woman it would be ok for me to date an 80yo man? No fucking way!!! It's a ridiculous rule!

It absolutely would be ok for you to date an 80 year old man. You’re both consenting adults why wouldn’t it be?

@Ilovemaisie

Cutie you could be twins with your sibling and have nothing in common with them or their friends. I go to a social group where you do have to be 18 to attend (because we meet in a pub) but 16/17 can come if they are with an over 18 person. We have had younger teens help out at events we have been part of. The oldest in the group are in the 70s, the youngest has been attending since 16 (but is older now). We all have one major thing in common - the 'hobby' we are involved with. It is possible for people of different ages to have shared interests. The OP is assuming this relationship between her niece and the 25 year old is a sexual one. It might even not be.

You have to be quite immature to have loads in common with a child. You don’t have much life experience and your brain is still developing. Sure, you can share an interest in a sport, fashion, computer games etc but adults who develop a romantic/sexual relationship with a teenager are creepy.