Is what I am doing morally wrong?

I've been with my wife for 20 years. We're in our forties. I've been staying with my wife for only. She is really good in bed and I find her very attractive. I had with other girls before but I prefer to have with my wife only. She doesn't know I am using her for . She thinks I'm very much in love with her. We have children already too. I keep on telling her I love her very much and I got a vasectomy so I can have all the unprotected I want with her. She doesn't want anymore children. I plan to be with her for the rest of her life and I plan to stay loyal to her and to her only. I've been supporting her and our child (for all the years we've been together) and taking good care of her. Is what I am doing really wrong? she has a really high libido. I get to have with her twice daily. even when she is pregnant, i had a lot a lot more sex than when she wasn't pregnant. I wish my wife had that high of a libido when she's not pregnant. When she's pregnant, I got to have sex with her like at least five times per day.