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 :)
Fair enough, I guess I'm just introverted enough to not have that realisation occurring by myself. Thanks for your response. Have a good day :)