Why do I resent my boyfriend for doing 50/50 for rent and groceries?

I know the people around me, my sister, her best friend and my mom all are taken care of by men who are providers and pay for almost everything. My best friend even says a guy should be a provider, as in pay for most things. I recently fell in love with this guy, he claims to love me too. At first, when trying to court me he paid for more things. Now that we move in together, He wants to do 50/50 and is very precise and last time bought groceries without me knowing and asked to split the bill. It was $200. I know we do eat it together. But it annoys me that it seems like it has to be exact amount I have to pay and that hurts me. I am the type to pay a few times or always get him something when he treats me

Why do I resent my boyfriend for doing 50/50 for rent and groceries?
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