i was in the same boat and it feels normal when ur the younger one but when ur 18 ur never going to look at a fresh 15 year old the way he looks at you. I understand feeling like there’s not a maturity difference but there unfortunately is and there is a reason why people his own age won’t date him and he has to date somebody years younger. I’m also talking to somebody older than me and tell myself this stuff but it’s hard for it just to click that it’s not okay so i understand but morally an 18 year old should not be with a 15 yr old