I could never love someone that goes to jazz festivals.

The amount of people defending this is weird, 16 is way too young. That being said, there isn't much you can do as his parent. Even if you do manage to break them up, he will always blame you and think of the "what ifs".

From your post, I can't quite decide what worries you most about this relationship... I've written and rewritten this comment multiple times because of that.

The usual concern with such an age gap would be that he might take advantage of her and her lack of experience. That's a valid concern that should be addressed. But It doesn't seem to be what's bothering you.

With you starting your post by telling us about his ex who is completely irrelevant to this story and your relationship with her, then later list off how great your son is and that "it’s not like he’s lacking options"... I can't shake the feeling that your problem is more with him having a partner that could be considered "below his own status". It feels like you would react just the same if he dated someone closer to his age but not as successful or good-looking. And to that I must say, that's none of your business. Let your son love whoever he wants to love. Let him make his own decisions and when it comes to it, his own mistakes. They obviously share some interests and he's old enough to decide if she's "good enough" for him.

This is creepy af. Someone in their 20s has a different mindset than someone in high school.

Dude is a pedophile.

That’s gross and as a parent you have the responsibility to tell him it’s gross. Don’t normalise this relationship.

The only reason grown ass men date children (laws on the age of consent were written by those same grown ass men, they don't dictate reality) is so they can have someone who hasn't yet learned how to recognise red flags to coerce and control. You don't need to actively encourage him to be sending him the message that you, at the very least, don't disapprove.

It's up to you to decide how comfortable you are with sending him that message, and act accordingly.

29?

I've seen bigger age gaps work out long term, but dang, not when the younger was still a kid in most ways. It comes down to there needing to be a certain degree of development of self before you can make a relationship be a meeting of equals where both people can move forward together rather than it being one leading the other (intentionally or not).

There's really nothing you can do about it, though. Like you said, he's a grown ass man and has to reap the crop he sows. If she's legal there, and the parents aren't objecting, there's nothing that you can the that's useful. You just hang back and see how it goes.

Treat it like you would if you didn't like his choice in dating because she was stupid, or ugly. If he asks, don't lie about your opinion, but don't bother them with it either. Trying to force them apart is likely to backfire and at the very least could make them stick together longer than they otherwise would if it isn't going to work out on its own.

People are allowed to make bad choices as adults. When it comes to family, there's a limit to what kind and degree of interference is acceptable, no matter what the family member is doing.

You've had the unfortunate discovery that your son is likely an idiot about at least this matter. Could be worse.

My first thought is REBOUND RELATIONSHIP. His long-term breakup may have been “amicable”, but it seems like it hurt him more than you (or possibly even he) realize. I think a major part of what he likes about his new girlfriend is being in a relationship where he clearly has the upper hand.

Whose idea was the breakup? “It was both of theirs” is not a real answer. Someone had to initiate the conversation. Who was it?

Maybe I'm the weird one here, but doesn't this problem literally evaporate in 4 years anyway?

I've never seen anyone bat an eye once both are over 20.

His current girlfriend’s parents know about their relationship & are cool with it.

Possible, unfortunately, but how did you get to this information? Anything short of talking to them directly I wouldn't trust.

Start with asking yourself why this relationship is a problem, but the last one wasn't. If your son dated that girl for a year she must have been 15 (or younger) when they got together. This in itself is kind of a red flag.

I personally think that this specific age gap (with one partner being in high school and the other in their late 20s) is really problematic. Not due to the difference in years but the difference in maturity.

In what ways specifically has it changed your perception of him?

The first thing is the younger party being protected and allowed to develop, which it sounds like she is.

For me the rough time comes from realizing that either your son is dating her for her age (legal I guess, but ick), or he has so much in common with a 16-year-old it's enough to carry a relationship, which... Dude, what did you do in those 13 years to not grow as a person, ick. I can definitely understand why it would change your perception.

Then again, there isn't really anything you can do about it, except express your disapproval every now and then, but make is easy for either party to end the relationship without an "I told you so". Of all the actions for you to not condone, this is pretty mild. He could have joined a cult, committed crime, or "date" a 12-year-old.