My significant others have never found out when I cheated on them.
Are you sure they have never found out?
Yes, I know they never found out. They would have said something if they knew.
It is wrong to be cheating on your partner, and also to be hiding this behavior from them.  Your significant other expected you to be faithful, and even if you haven't been caught yet, if you keep cheating, you will eventually cause your relationship to end.
Life is hard and people get too used to each other. We all need some excitement and change in our lives, especially when it comes to sex. I don't think cheating is a big deal since it's just a brief exciting change of pace.
I just think it's a bit immoral to lie to your partner and cheat on them. Maybe you should just stay single and that way you won't be hurting other people when you sleep with women.