Is it just male nature or what??

I find it extremely disrespectful if a man checks out a woman (or man in some instances) in front of their partner. same with women doing it as well. I never pay attention to another man nonetheless even find any other attractive because i’m extremely infatuated with my guy. he does this quite frequently, claims its male nature and it just pisses me off and no matter how much he tries to justify it, it won’t ever make me feel better about it or give a benefit of a doubt, nothing. are men not able to actually make themselves not focus/stop themselves? do you think it’s disrespectful?