I absolutely agree about the communication. I've never had any problems talking about anything with my wife, so I can't really empathize with couples that this has been awkward for.
If my wife wanted to go masturbate some night instead of have sex, that would be fine with me ... as long as it was in moderation and didn't completely replace sex between us. I'm pretty sure she feels the same. IDK, sometimes you just want to take a bubble bath with scented candles and a vibrator ... sometimes you just want to have a quickie when you come home for lunch before a stressful afternoon presentation.
My wife and I both masturbate, but not all that often. We mostly reserve it for when we're away from one another for a while, like when she was in Australia a year ago on business for 10 weeks. Or when my father died suddenly about 4 years ago and my wife flew back home after the funeral, but I took a sabbatical from work and stayed to take care of the estate for the next couple months. We just made some pictures / videos for each other during both those periods apart.
On a day-to-day level, we masturbate maybe a few times a year. It's often because our libidos are slightly different. It might be bordering on TMI, but there is some internet anonymity, so why not: we have masturbation races ... where we lie down on the couch and make out for a minute or two then masturbate until one of us climaxes then we'll take a shower and go to bed. We'll repeat this each night until the other person climaxes first. This never takes that long and usually evens up our libidos since more often than not I'll finish first for a couple days before she beats me ... at that point we're both satisfied for a week or so until we have sex again.