I feel like I’m in the way...

Idk how to feel. My SO, and his ex wife have a 6 year history together. A while back he had a chance to get his old job back Bc of her help. He didn’t take it tho. He gets jobs here and there but quits Bc he isn’t happy with them. & I feel as if it’s my fault. Every time he got with a girl after her, he has gotten back with her after 3 months of being together. We have been together over 7 months now. He is in the army. A week ago he decided to stay with a friend.. when he got home the next day I found a paper and just out of habit I was gonna throw it in the floor😂 but I wanted to see if it was important before I did so. And it was a receipt for a hotel. With his ex’s name on it. He had her bring his laptop to him. So I’m not sure what to believe anymore. I paid $500 to help get his car fixed and I feel like I’m not doing enough for him... I feel like she helps him much more than I can and I try so hard. Idkk. I really don’t. I tell him just to go back to the nursing home where his ex works. But I know how that will end..