One comment that I've heard has been "how did a guy like you, get a girl like that?"
You seriously got offended by this? This is like the biggest boost to your ego, or should be.
If I had overheard something similar I would just ignore it. If someone would say something like that to my face, I would respond "Because I am cool and you suck" and walk away. Seriously, why the f*** it matters what other people think you deserve or not.
And next time, pls don't talk about that with your girlfriend. It just shows insecurity. You need to believe in yourself, that you deserve that girl. Everything else doesn't matter.