You pay ALL the household bills, but the second he needs to cover a bill (something as little as gas) he expects you to pay your way. I.e. what is yours is his, and what is his is his. You aren't partners, you are being used.
My own dad (who gave me one of his businesses) pays for his wife's university course, driving lessons, food, bills, clothes, days out. Everything. Because she's decided she wants to do a sports degree at 40 and not have a job.
My mum's husband did the same thing for her when she quit her job to do a psychology degree (apart from she paid for the course herself). People think that's so good of them and that they're such good husbands. The views seem to be very different when it's the other way round
Both of these examples, on their face, are very different to the situation you describe with your boyfriend. In your examples it sounds like the people have actually worked and done something productive in their lives and paid their own ways before wanting to do something different. Also likely they didn't just make these decisions themselves and instead did so with the blessing of their spouses.
And no, my response wouldn't be different if the sexes were reversed. My DH's best friend is in a relationship like yours. His girlfriend makes financial decisions for the relationship without any care for the actual effect on the relationship. She quits her job, get's shitty jobs, and expects him to pick up the slack because he earns more. She'll buy stuff and expect him to pay half. It's all kinds of messed up and it's pretty damn obvious without him she wouldn't be making these decisions because she wouldn't have someone to pick up the slack.
To answer your OP, no, YANBU to expect not to pay half. YABU to not realise there is far more wrong with how things are than just him expecting you to pay half for gas. His friends and family are more important than you. It's okay for him to do them "favors" but got forbid he pays his way with you.