Isn’t this rude

So I was placing an online order today and FaceTiming my boyfriend. I told him the store and he’s like “I have a $10 gift card that I will never use, use it and give me cash” I was like no I don’t want it that’s fine, mainly because it wasn’t like it was helping me since I was gonna have to pay him back. He got all mad and I was like it yours just save it and use it for yourself. I hate accepting things from people especially when he was just doing it to get cash off me. I told him it’s not like you are being helpful since I would have to pay you back, I don’t work (College) and he does and he said he was never gonna use it plus it was a gift. We’ve been dating for 4 years and talking about an engagement so it bothers me that he thought I should have to repay him. It was only $10 so it’s not a lot, obviously if it was $30 or more I would have paid back but $10 is such a small amount. If we are gonna get engaged soon shouldn’t the money mindset be more here let me help you/ you help me next time??? I have put gas in his car, covered the tip when he was short (he’s dont this for me as well) but still it’s not like I do something for him and expect him to then return the favor immediately. Opinions? I’m just shocked that he thought I should give him money for helping me out... I should add that he is kinda snobby (mainly due to how he was raised) and that his job pays very very well so it’s not like he needs the money (car paid off, parents have a gas tank at house so free gas, lives at home due to college). I’m sorry if it sounds petty but I don’t want to be married to him if everytime I borrow money he expects me to pay him back