Bebop, I'm sorry...you must feel very lonely and left out. This, I believe, is a time in your life when some soul connected cuddling would be very supportive for you. That need unmet can be so crushing.
My take on men is they're like little volcanoes. They go zipping around in their life and then every few days have to "take care of it" one way or another. I think that's normal, until and unless it get's in the way of the marriage. When it replaces normal sexual relations, then it's a symptom of other issues.
I don't consider masturbation as cheating. And, him masturbating is better than going outside the marriage.
There's no reason you can't masturbate too. Maybe you could migrate to masturbating together. That can be very stimulating. Maybe you could try talking about it. I think finding a way for both of you to connect on some level would be a good thing.
Again, sorry things are so strained. Some couples counseling might be helpful.