I'll intro in OYS, but brief background: married 15 years, 3 kids from 5-13, sex life was shit. I'm 40, and getting my shit back together- lifting, reading, leading life.

The test: I'm bald. Saw a pic about 5 years ago with a lot of scalp, took the clippers to my head. Wife screeched- she likes hair (tough shit, it fell out). Started shaving with razor about once a week 2 years later. She bitches. As we went pretty close to dead bedroom, I just shaved it every 3-4 days, as I was lifting heavy and liked the look. About 6 months ago, shit had come to a head, I made an overt contract- she can use clippers on my head when needed, she'll be more attracted, more sex (she expressly said all this, thus not covert?). Ha ha ha. Guess what?... swallowed the pill, shave my head, she bitches. Started fooling around last night, she keeps at the hair thing- I got up and left. Came to bed after reading. Now she's horny, trying to be cute- grind a bit, then "say yes you'll let it grow". I just look at her. She keeps it up 10 minutes, I get up, put my boxers and shirt on, and roll over. She starts to get petulant, asks why I can't do what she wants. I tell her- "personal hygiene, it's personal". But I like it after about a week. I tell her that's the point it needs shaved. I'll worry about my head. She should worry about the other head. She quits the topic, I get head and fuck her.

TL,DR- exercise OI by refusing to comply with wife's desires (hair) in exchange for what I want(sex, what else?). She'll turn off the tap because that's ceding power. Do what I want, still get what I want. I run the show.