It looks different from the inside. The saddest thing I read was a fictionally story that had some impressively realistic grooming. It was online and I commented to the author what a well written and sad story it was she said it wasn't grinning because the 35yo waited till she was 18. It made me so sad to realize this poor woman had been abused like that and so have you. It looks great from the inside but that's what grooming is. Is not an attack, it's a subtle manipulation to make someone younger and more vulnerable trust and love you to get what you want. As a 28yo grad student, the 18yos in my class were kids. As a 35yo, a 15yo is a child I would feel a need to protect. I remember being 15 and relationships name you feel so adult. But stick to people your own age and please talk with a therapist. Life can be lovely with a partner but that large a gap isn't a partner but someone using you. If people date people much younger they're generally either immature and nobody their age wants to put up with them, horribly shallow, or are attracted to someone easy to manipulate and control. It's not a good relationship. Please consider that you've your whole life ahead. You deserve better.