Yes, I masturbate in front of my wife many times. Sometimes we will be in the shower together and I'll just jack off there. She enjoys watching my cum load shoot out. Lots of times we will be in bed and she will ask me if it is OK for her to masturbate me. Usually if we are in bed she will roll on a condom so as to not get the bed wet. Frankly, I really enjoy feeling her hand around my hardness and watching her jerking me off.
Lately we have done a semi-masturbation. I will get a hard on, lube my dick and her, and slip my dick in her. Then I will pull out and just leave about 1 or 2 inches of my dick inside her. Then with a latex gloved hand she will reach down between her legs and grab my dick and masturbate me while the head of my dick is inside her. It feels extremely great and is fun to watch between my legs. And she enjoys having me shoot my cum load inside her also. You should try this, as it really feels good.