When I’m talking with women (especially women I’ve just met), I mention my wife as a way of signalling, “I’m not hitting on you.”
I mention my wife in conversation when it is relevant. She is important and instrumental in my life so she gets mentioned a lot. So do my sons.
If a married man flirts with me he never talks about his wife.
If a man out of the blue mentions his wife /girlfriend I take it as a hint that he’s not available for a flirt.
Here’s the recent thread about the same issue from the other gender POV: Women feeling the need to reference their boyfriends (to reassure themselves?) - In My Humble Opinion - Straight Dope Message Board
Sometimes. mentioning a wife/girlfriend may be a way of putting a female stranger at ease. The implication is, “Don’t worry, I’m not going to hit on you. I’m happily taken, so I’m safe.”
I wear a wedding ring, should take care of any misunderstanding. And I’m quite a catch, according to my wife.
Edit: I guess she has to say that, otherwise she looks like she settled.
Guys in general at not that aware of what is going on, or pick up on subtle things. If a woman is flirting with a guy, she has to practically hit him over the head with it for him to fully understand she either has an interest in him. Guys are not used to women flirting with them so they don’t expect it unless they have this massive ego like the character Fraser in the TV series by the same name. So if they mention a wife or girl friend, it’s because it just came up in conversation the vast majority of the time.
If a guy is really not interested in a women, he’s not going to give her any attention or look to end the conversation. Not to be rude, but he isn’t interested, available or distracted at the time.
If that’s the case, he would drop that his ex-wife was an underwear model for Victory Secret, but he didn’t like her being on the road all the time because they couldn’t spend time on the yacht that he bought just for her, her favorite color too. 
Come on, you know very well, if they have to explain gay sex to their kids their heads would explode! It’s a safety issue.
I don’t think it means anything specific. Sometimes it’s just conversation, sometimes it’s the guy making sure you know he’s not available. And sometimes–well, I have known a guy who mentioned his wife, mentioned he should spend more time with his wife, mentioned how highly he regarded his wife. In between all these mentions of his wife he was definitely hitting on me. Maybe it was some approach-avoidance thing.
That’s my excuse, I mean reason. Most of my anecdotes from adulthood involve either my girlfriend or her predecessor. No more significance to it than that.
Plausible deniability?
Funny, I recently witnessed a buddy drop what I call the ‘gf bomb’ on a girl flirting with him. In fact we were celebrating his girlfriend’s “Target is closing in Canada” party where it was her last day as a manager.
I can’t say I have ever used this tactic, but I am pretty sure women have unnecessarily and gratuitously done it to me a few times. Usually I ignore it because it doesn’t mean anything. They could be reassuring themselves because they are attracted, or being skittish. Either way, it doesn’t help anything to overanalyze. Just keep moving the conversation forward and let it evolve organically. Someone having a s/o doesn’t necessarily imply monogamy or fidelity.
In fact, if they mention their s/o I just assume a standard topic change and run with it.
They boyfriend-bomb me from orbit. Because it’s the only way to be sure.
Ok, so guys are jerks for casually talking about their wives or girlfriends in casual conversation.
And guys are jerks if they don’t.
And if they talk about the Marvel Cinematic Universe it doesn’t matter.
I’m wondering why older men manage to mention their wives in an initial casual conversation. It makes me feel like they think I’m flirting with them (I’m not). Are they so not used to a female talking to them that they don’t know what to say? I’m older myself and this has happened even in a hardware store when I’ve asked the employee about a metal window lock. I don’t understand why they feel this is necessary.
This is exactly the reason. Good job, you figured it out.
Then read this thread. Bam.
Exactly.
Guys who aren’t on the prowl aren’t thinking that hard. Mentioning their wife could be a result of their wife taking up a large portion of their day to day thoughts.
I could absolutely ruin you for other men. I’ve done it before, but I won’t. So tell me more about this window lock?