You ever try putting up with MEN in a relationship? That is even worse by a huge margin.
I eat high protein for the extra calories it provides. I am not big on carbs, so I have to get my calories in somehow. Calories are the name of the game when it comes to building muscle. You have to get enough to grow. So I opt to use protein for my calorie needs.
Some people debate whether using more than 1g or 1.5g per body weight is a waste and non productive. However, it has definately helped me.
I am only 29, so I don't know about adding mass as you get older. I do know when I finished college, I added mass very rapidly but only because I was not doing cardio and intense swim drills and comps all the time. Some of this mass was fat, so I learned to cut my carbs back to keep the fat off. Of course, the gains slowed and stopped and I learned to up my protein (and calories) to get the gains coming back again.
I took a lay off from the gym and the bodybuilding lifestyle completely for about 7 months and thus lost a lot of size, but when I came back, I resumed the same approach, high protein and low carbs and started growing all over again.