Proper Behavior for an Engaged/Married Relationship?

No, you are not wrong to be offended at all. It is ridiculous that you pay for pretty much everything for you two from what you're saying and that all he actually pays for is the gas money. Wow! He shouldn't be treating you like that! You never ask for money from him and you offered to pay the gas money before and you do periodically. He is in the wrong here and you really should reconsider being engaged to him let alone marrying him. He has a good paying job, lives at home, no bills, no nothing pretty much to pay for except gas! This guy has it made between you and his mom and is making a deal out of you not paying for gas is just crazy! Imagine what it will be like if you marry him.