Advice on a FBW situation?

I am 20 years old and currently in a friends with benefits relationship with my ex boyfriend who is 40. Don't try to be negative about the age gap, because we are very close and age is only a number. A serious relationship wasn't working for him so this is what we started doing. My question is, he's busy a lot. He works out of state frequently on jobs, and he works late. We only get together once or twice a week, sometimes not at all. I really want to have someone's company, but I can't be with him very much so that upsets me. Would it be wrong of me to find someone else to sleep with? It seems like a slutty thing to do, but maybe I'm wrong. I just hate being alone all the time, and want someone to be there more than my ex is right now.