Okay, I'm 22 years old and I masturbate quite often, I've even gotten a flesh light and used it quite a bit but I notice that it desensitizes my penis quite a bit with frequent use, and when I have sex it takes me a long time to climax, now its not bad for my GF but she noticed it as well about a week ago that its taking me longer. My penis just isn't as sensitive, I'm pretty much just going to stop masturbating since I know this is the cause, and I only have sex a few times a week. I'm honestly like, really addicted to sex, sometimes me and my GF would have sex 4 times in one night, and then I masturbate a lot as well, does this make me a sex addict? Is it unhealthy to really do this much with your penis? I'm just worried if theres going to be problems with sensitivity in the long term, or if I just stop masturbating my penis will eventually gain its sensitivity back?

You pretty much are answering your own questions. Yes you are not helping things by masterbating so much. Actually you shouldn't really be doing it at all if you are having sex on a regular basis. Are you a sex addict - well I would say you are addicted to masterbation since you are doing it so frequently even though you are having adverse side effects. Suggest you quit doing it all together and just focus on being a good sex partner instead.