Oh if they are coupled up and on OLD, they're most likely looking for an affair, or a penpal.
Sorry, I do realise my comment reads a bit weird. It's just that in my experience adult relationships are complex and a bit messy. E.g. they could be single, but still hanging out with their ex wife regularly (see Will Smith and Jada for example, IME this kind of dynamic is increasingly normal the older we get), could be dating someone for 3-4 months but not serious about them, etc... Could be hung up on someone who won't date them... Could be in a casual long-distance relationship, see the guys BoxOfCats is seeing... It's not so black and white until you know them better, whatever they say or post online isn't necessarily the reality.
For example, I've been dating Mr RedFlagParade casually for a few months now but it's not headed anywhere serious, so if someone asked, I'd say I'm single. If I was into them and they probed deeper, I'd elaborate.
I just don't want to use up headspace to wonder 'who is that Thalia that keeps commenting on their pictures' until that's actually my business. I would expect a guy that's a catch to have other women after them as well.
If you mean coupled up as in married or living with a partner, then yes that's something I'd be more interested in knowing, but that's usually very obvious.