Is it normal to constantly switch genders in sex partners?

I've known I was bisexual all my life. And, I've been in many, many sexual relationships (500+), along with a few really special love interests, mainly women, one guy. Most of the sex has been with women. Now that I'm in my late 30's though, I've had a much easier time picking up young, hot, masculine guys. I don't know if its the Internet, my power position and age or the fact that I'm more confident in my gay side. However, as lonely as the single life can be, my pattern has been to leave the relationship with a woman before it goes to commitment level at the expense of settling down and having a family because I don't want to give up sexual relationships with men. There's something exhiliarating about a secret and hot ongoing and intellectually stimulating connection that is also, on another level, disgusting to me and would be to any woman I'm with if they found out. So, is this normal and I'd appreciate some real and honest answers.