I don't know if this is really common or not - but as a simgle woman I do perceive a sense of awkwardness if I am talking with a bloke and his wife isn't there/sees us talking.
It might all be in my head. Next door's husband is not very good at DIY (I've been told this by her family) and I came home the other week to find him struggling to fix the hinges on the front door.
I made a polite comment and he told me what he was trying to do and I said I had the right tools, and offered to help - I think he was happy to accept, so I got working on it and then his wife came back from somewhere (I had assumed she was in the house) and seemed a bit shocked to find me helping with the door.
I was really embarrassed. The thing is perhaps it did overstep a boundary in that it's a couple thing to sort out, I get that, but he was clearly having trouble and panicking a bit.
It didn't occur to me not to help, or whatever - it's something I'm good at and have loads of tools and so on hanging around.
Just the thought that she might think I was stepping on her toes or after her husband makes me blush as for one thing I'm not after a bloke, secondly I really really don't fancy her husband, and thirdly I really like her very much and there's no way on earth I would try and - well, whatever it might have seemed like I was doing.
I am lonely as a simgle parent and I like to chat with men or women but that is where it stops. It makes me even sadder and lonelier to think I'm counted as a threat but I can see how people might automatically think, 'she's available, she's good with a drill, maybe he might fancy her' - but as if that was all there was to a marriage? It doesn't compare to what they have built up over the years.
Also I think when you're married too there is seen to be an official boundary set in stone between you and their husband.
When you're not, the obvious boundary is missing, so people sometimes think they need to establish one, in case you are a threat.
It doesn't offend me. It's just a bit sad.