Pegging Your Wife or Being Pegged?

Hi there. The issue is this: my wife wants to peg me using a strap-on, and I’ve let her try it out. However, once she has the device in place, I start grumbling after just a few thrusts. We aren’t into sissy or cuckolding dynamics; we simply enjoy male chastity and her taking charge. She really likes the power shift when she positions herself behind me to peg me from that angle, but it seems my reluctance stems from perceiving it as something gay. I’m not sure if that’s truly why, and I’d love to get more out of it. Has anyone else dealt with this or have any tips?