I guess you can answer this better than anyone. I checked out some of your other pictures posted to your profile and I can tell you're older like me and my wife. My guess is you've been together for a long time which in turn makes me think that you aren't so afraid of her leaving you for a better fuck. You're also probably comfortable with each other in other than sexual ways.
If you are happy doing what you're doing then go for it, fuck what anybody else thinks. On the other hand, if you're getting more humiliation than you want, or too much denial then speak up. If any part of you is feeling anxiety or reluctance you'll begin to feel resentful over time. If you don't like doing it keep your sanity and say no.