I (39F) am in a open relationship with my partner of three years (26M). I've always felt younger than my physical age - currently mentally identifying around 27-29 - so I've always been more attracted to younger men as well as a result.

My partner is bit of an workaholic and on the spectrum, so he needs a lot more time on his own. This wasn't a problem before, but then we moved bit further into the suburbia so now if I want to go downtown, it's either an hour by public transport or 20-30 mins by car. I've felt bit cut off lately, and have been asking more attention from my partner which has irritated him. We had lot of arguments about this, and finally my partner suggested that I should find someone to keep me company few times a week when he's busy. We then decided to open our relationship and so far it's worked great - he gets his me time and I get abundance of attention in Tinder from guys 10-15 years younger than me.

I've now met a guy from Tinder who's sexually near perfect match for me. We share kinks, he's eager and willing, and being ADHD as I am, he's down for spontaneous dirty stuff like having quickies in public. Having him in my life is like having a living, breathing fucking machine - his stamina is otherworldly and even after orgasm, he can keep going without so much as going soft in between.

The issue for me is our age gap - he just turned 18. He looks and acts like someone who is 25, and I first thought he was just fucking around with his age in Tinder to get younger chicks, but then we met and he showed me his passport to prove that yup, he was indeed born in 2004. We have 21 years between us, but me being more childish and him being more mature for our respective ages, you really couldn't tell we were that much apart.

I'm now worrying whether being involved with someone so much older, like I am, could be somehow mentally damaging to him since let's face it, he is still a teenager. He is of legal age and therefore I'm not committing any crimes where I live, everything we do is mutually consensual, and there is no sugar dating aspect involved. He's just a fun guy who is equally horny and slutty as I am, but I could be his mother by a fair marginal.

He knows I'm in an open relationship, it's not a problem to him nor to my own partner (who is just amused by my choice of men). But he seems to be more attracted and attached to me than I necessarily am to him, and this worries me slightly.

Just keep going or break it up for his sake?

TL;DR: Having sex with a guy who's 21 years younger than me and worrying whether the age gap will fuck him mentally in some way.