I think you're overreacting and I don't think his actions are disrespectful in the least bit. Me thinks you wanted to have your cake and eat it too, but you've since discovered your cake has a tarty cream filling. You said you're just FWB and not only that, you're in a relationship with someone else (does your main dish know about the extra helpings you've been having on the side?) So he acknowledges the beauty around him, I do it too and I don't care who I'm with. Their insecurities are their insecurities and that's not my problem; perhaps that's how he feels as well?