Weight loss and gain

So I went from 210 to 125 in a year and a half. 6 months ago I started gaining weight again and now am back at 160. It's been a real struggle. I gained over 30 pounds while in my current relationship. I feel extremely insecure and I'm starting to think it's done something to our relationship. He says he loves me no matter what but I still can't help thinking that. I want to lose weight for me but no matter how hard I try I seem to gain weight instead of losing it.