Why do people think its emasculating that my girlfriend is the breadwinner of the household?

Like I don't get it. My girlfriend is a successful woman. She studied computer science and is the head of the IT department on a quiet big local company. And she makes more than I could ever dream of. I currently work a minijob at a local electronics store three times a week and if I'm not doing that I stay at home, take care of the household chores, cook something for her or take care of our pets and the garden. And everytime I mentioned that people, mainly men look at me like i'm an alien or something.

And my father told me its a shame that I made myself dependent on a woman like come on. You're the reason my childhood was shitty and now you wanna blame for not being able to have an education like she does? And overall what is the problem with it? My girlfriend loves me and I love her. I take care of everything around the house so she doesn't have to when she gets home from work and she spoils me like crazy.

What is the matter with that? As long as we're happy just do yourself a favor and mind your own business!