I miss having sex with new people

In my early twenties I had a really bad heartbreak. My ex who was my first love cheated on me with like 3 girls. It ruined my self esteem and after we broke up I felt like I had something to prove and slept with a lot of guys. It was probably around 20 guys in the span of 1.5 years. The sex wasn’t always good but it was always new and exciting. Some of the best sex I’ve had was with those one night stands or brief flings. I still think about it sometimes. I met my now husband when I was 25 and he was one of those flings. We’ve been together for 8 years now and I haven’t slept with anyone else after our fling became more serious. The sex was very good at the beginning but it’s just not exciting anymore after 8 years. I keep thinking about how even boring vanilla sex was good when I was with someone new, and I can’t get that anymore because I could never imagine cheating on my husband. I feel guilty to even be missing having sex with new people.