I want to punch a gay person for staring at my partner.
Why does a gay person staring at your partner bother you?
I don't like the way they look.
It's really annoying when someone else stares at our partner, but punching them is never a good reaction. Reacting to minor social offenses with violence is likely to land you in jail. Either politely ask them to stop, or just ignore the behavior.
They deserve to be punched because it's the only way they will learn.
No one deserves to be punched. Don't let your emotions towards this person's staring at your partner get you into trouble. Just walk away.