Wow, yeah.. you're only 21. Why the hell are you prophesizing your "death alone" so young? As far as being a nice guy goes.. I know from personal experience it's way more rare to find someone with a decent, respectable personality over a thoughtless bastard. This whole psychology that women are only attracted to jerks apply to some, sure, but definitely not all (so don't go using that as an excuse). Besides, why would you even want to be with a chick who wanted you to act like a moron? Totally not worth it. So don't sell yourself short, yanno?
Anyhoo, as with most things in life, it takes time. Put your focus on other aspects of your life for now (studies, hobbies, etc), and work on building your self-esteem, man! Confidence is essential! Then, you'll notice everything will fall into place.
Trust me, you'll find someone. Don't expect perfection, though. If you do, then there is no way to go but down, since being perfect is the peak of expectations (perfection will build over time, once all flaws are accounted for).