It's probably meant jokingly but I find it a little too much too.
Maybe more something like "You can approach me platonically." or whatever. Just because I'm in a romantic relationship with someone does not mean I'm not allowed to have friendly relationships with other people.
Every friend I've ever had turns out to only be looking for like minded enablers to justify their drug or alcohol problems. And when it turns out I disapprove, they do something shitty like steal your tv.
And every woman I've ever dated turns out to be either "dating you for a place to live", "dating you to make her husband jealous", or "dating you to be dating SOMEONE". I've never had someone who is dating me for me. And I've never had a friend who enjoys sitting around every few weeks, getting drunk, watching some sports, but then the next day you live a sober life. It's always me basically babysitting a drunk, or me trying to play dr phil to a guy who's threatening to beat his wife.
Before I end up realizing "fuck all these friends. I'm going to sit in my apartment alone, and watch ghostbusters on dvd, while wishing I had time for a cat.
Gotta be honest here, my gf is not the jealous type at all, and i would rock this shirt if I had it. Wording could be better maybe but i honestly think its kinda cute
You know, some people might just be committed and love their SO but still go out to bars and clubs and find the shirt funny and possibly useful. But the shirt isn't inherently saying my SO is jealous. If it said boyfriend and a girl was wearing it would you say the same thing? Most times no.
Overall some people enjoy their SO and has no intention of cheating and like the idea of just showing their commitment publicly :)
But it doesn't say "I'm unavailable but still down to socialize" it says "stay away from me". I interpret the implication to be that it would be bad for the wearer's relationship with their gf if someone approached them.