If you feel guilty about masturbating, find someone who's addicted to sucking dick.
More seriously -- it took me a while to learn, but for starters there's nothing wrong with masturbation. Unless you're in a position to procreate, all the sperm and semen will just end up coming out in wet dreams or getting reabsorbed by the body, so you're not wasting anything. I think the biggest reason religious types are against it is because, well, it FEELS GOOD! and you're doing it for yourself -- but that's no different than a hobby, which makes you feel good, and you do for yourself... or like working out, which pumps out those endorphins or whatever, and makes you feel good.
For some people, masturbation brings feelings of guilt because it's so lonely -- whereas sex doesn't, becasue there's someone you're sharing with. There is certainly something about sex that begs for sharing, but that doesn't mean that going it solo is wrong, just less satisfying. For me, I have never reached a point of joy when doing it alone, while with a partner I have several times reached that point -- joy, thrill, excitement, even exaltation.
At base, remember that you own yourself. If you want to bring yourself pleasure all by yourself, it should be fun.
As far as a partner getting upset every time you make love... I've been raped, and I have guilt feelings after sex, sometimes. But if there's no traumatic memory, you have no reason to feel bad -- so go for it, solo or with a partner (or two)!