Found his dirty towel

So I have come across the masterbation towel under the nightstand. I am disgusted! I know it's a normal healthy thing to do but feeling disappointed and disgusting because our sex life the last 6 months has gone down. We dont do it enough anymore only during peak cycle. And there are days we dont see each other for 60 hrs a weekend due to my work schedule. Even when I ask him why he does it or if there is something g wrng he just states that I never want it or I'm too tired, starting to feel like it's all my fault he's doing this and him leaving the dirty towel is a sign he's not happy with me or our sex life. Ugh idk what to do anymore. And talking is making him upset.