Don't know what to do with this...

No need for you to speculate about whether the 16 year old has cause for complaint.
We all know that some men, however busy they are, can find the time to make women and girls feel uncomfortable. And we all know that while anyone can look at anyone, there is a particular way some men have of looking at women and girls that makes us uncomfortable. And we should all know by now not to dismiss a woman or girl who says this has happened to her.
Equally we all know there are possessive, jealous boys and men who might have their own agenda.
So, as I say, speculation is pointless, as you can't possibly know if there are grounds for concern here.
You are simply a go between. So go to the one in charge and repeat what the 16 year old had said. Say you're not making accusations, but thought you should pass it on.

Interesting language. A boy raising a concern about the way a workman has treated his GF is "ordering you around"?

At no point does OP say he told them what they should do about it.

Yeh you tell the neighbours that the company name is x so they can contact the company if they wish but they are almost finished.

weird neighbours

I'd leave it tbh. Not dismissing how she felt but it's hard to say anything when you don't know what actually happened

The worker may or may not have been looking at the 16yr old inappropriately, leading her to feel uncomfortable.

I think the crux of the specifics here is that this is your neighbour's child. If anything untoward has occurred then you should be dealing with it with her parents, and not her boyfriend. I'd have thanked the boyfriend for coming to do, but it's best that the daughter speak to her parents and that the adult's will be the ones to talk it through together.

Look, I'm just batting back and forth with you, nothing bad intended! I would be totally sceptical about a young boy 16 approaching me about something unverifiable, something I didn't do, and something I am expected to solve, without his girlfriend beside him to back him up. Even then I'd tell them to come back when the workmen are here and say it to them (with me there if needed, albeit reluctantly).

I mean if the workmen deny or ignore him/us what's the next step?

I hope they are all back at school today and have forgotten all about this nebulous thing that may or may not have happened anyway. The angst of youth.

Those kids have got looooong, headache-filled lives ahead of them if this is how they are!

I don't think the girl has said anything to her boyfriend. I think he's seen other men at the next-door neighbour's and is feeling insecure and threatened and is trying to piss on 'his' territory (which of course it isn't anyway). He might have seen one of them glance towards his girlfriend, as you do if someone walks past or comes in or out of a door in your field of vision, and has jumped on it as his chance to square up.
I'd just ignore. He's being a silly kid.

I would probably put up a ring doorbell camera or some such and let both workmen and next door know. So next door know that next time he looks at her funny it will be caught on camera and she has the reassurance of that. To the workmen I would probably say nothing except it's there.
That way you've kind of unofficially dealt with it in a way that doesn't upset either.

Perhaps, but it will have come about becuase of all the great work being done in schools to tackle misogyny. Boys are being taught to call out the behaviour of men and boys. What a shame adult women are so dimissive.

It doesn't matter if it's real or imagined. No accusations need to be made, just a reminder that respect is expected.

I'd probably speak to her parents saying that boyfriend told you of an incident which left girlfriend uncomfortable and can they add anything/know anymore before you speak to workmen.

I've told workmen "next door is very particular about parking, please dont park in x or y to spare me the agro" - it needs a similar conversation to that where it doesnt dismiss what the neighbour is saying. You dont know any more to say anything further.

I would be annoyed I was put in this position. Don’t say a thing and don’t answer the door if the neighbours boyfriend comes round again!

Vulnerable to predatory men ? Is that what you meant ?

Yeah don't say anything. Why would you want to ruin your relationship with your builders by implying they were perving on a schoolgirl?

If this boyfriend has such an issue then he should confront the alleged culprit during the act. Obviously don't tell him to do this though!

Quite the opposite surely ? He’s trying to protect his girlfriend who felt uncomfortable?

Surely this is one of those situations where a quiet word with the workmen along lines of, "we have teenage girls on the other side who can be a bit sensitive about strangers in their space etc. Can you please make a point of smoking /taking breaks away from their house - feels like the best way to keep everyone happy."

Honestly I despair. The idea that the boy, a child, should be expected to approach them direct when OP is scared to ask her DH to....

The sensible thing to do it tell the boss that you have received a complaint that a neighbours teenager felt uncomfortable, that you know nothing else about it but are passing it on. Then you have fulfilled your responsibility to both her and him.

He could say it to the girlfriend's parents, and so could she in the first instance. But that would prevent him from boasting to the girlfriend about how macho he is. There was no need to approach OP as he did in the first instance.

I'm getting far too involved in this. Need a coffee break!

God this is depressing.

A girl feels uncomfortable based on how she's interpreted a look. She tells her boyfriend. Her boyfriend comes over and politely reports the issue to the employer.

Why on earth is he seen as a red flag, that the girl is lying, that they are immature etc.? This is exactly what I would hope would happen if their was a perceived issue.

I would speak to the bf/gf when you see them, say thank you for letting me know, and let them know when the workmen will be finishing up and if there are any further issues to make a note and let you know. You don't need to do anything at the moment, but I would acknowledge it with them.

Maybe the parents decided on the approach most here are recommending....

I do wonder if some of the people here actually know any 16yos. Some are undoubtedly cocky little shits, but that's by far the minority in IME, and even they deserve to be heard.

Speak to your neighbours - not your neighbours child or the child’s boyfriend. Let them know about the complaint and ask what they would like the resolution to be.

That was there is the opportunity for it to be taken further if necessary but also the child’s parents are made aware of a potentially controlling boyfriend.

I wouldn’t say anything either. As you said yourself it’s highly subjective. It may just be his face, he may have been staring into space. I stare when I am thinking and somebody at work asked me why I had been staring at them and if I wanted them for something. I had not realised I was even looking at them!