I feel sorry for any of your unwitting significant others O.O
Sex is alot of different things to different people. Yes, some people are obsessed with sex, and yes, some people will go to any sick measure to satisfy themselves. This, dear, is called rape and people get put in jail for it. As far as I know however, the majority of people I know are not rapists, so I don't know what you're so upset about. Sex is a basic human desire, just like hunger and thirst. My boyfriend eats all the time, and I wonder how he's still hungry, because I don't eat that much. Sexual desire is the same way: some people just need it more than others. There is nothing wrong with this. Sex in a relationship can complicate things, but it can also bring the couple alot closer both physically and emotionally. Personally, I'm very much for sex, but there are some people who really should avoid it. If you're not mature or stable enough to deal with any possible causes of having sex, then don't. If you don't want to have sex, then don't. Whether you want to or not, it's okay because it's a very personal descision, but please, hon, don't go around degrading others for where they find pleasure in life. This isn't Victorian England--sex is acceptable and we have many modern safety measures we can take. If you're problem lies in the concept of purity, well, I could go into a whole second speech about that, for I don't even believe in the concept.
Anyways, sex is a very natural thing, and I don't think there's any reason to deny something your own body tells you. I enjoy it and I find joy in bringing sexual pleasure to my boyfriend. I really don't see the reasoning behind why you believe sex is wrong. Feel free to explain more, but that is my veiw