Nothing wrong with more girls; actually, most of my friends aren't guys. Spending non-sexual time around that girl might make you even better at talking to women. Maybe she has a single friend or two?
First about the ego / rejection thing: I'm afraid that's the price you gotta pay. Unless you're incredibly handsome / rich / famous, get used to either rejection or loneliness. Getting into the dating game (whether you're looking for sex or a relationship) is usually a humbling experience. Then again, it also teaches you a lot about other people as well as yourself, so put on your armor and head out; getting knocked off your horse hurts, but that's just a part of the deal. The other parts (the excitement before your success or failure and, of course, the successes) are worth the bumps and bruises. As for the first bit: there's a difference between casual sex and hatefucks. The latter is a case where you truly don't like the person you're having sex with, but that's pretty rare (I hope). I always saw casual sex as meetings of two (or more) lost souls seeking comfort in one another on their quests to find their true soulmates, to put it in a cheesily poetic way. Sorry, it's now safe to set aside the barf bags. Anyway, I think it's important to... learn (I think that's the right word 'cause for most of us it takes some rewiring) to distinguish between different kinds of beauty and to learn to appreciate them all. That way you'll see beauty (including the inner kinds) in almost everyone and when you go talk to them, your interest will be genuine, which is essential, because most girls can tell when a guy is just looking for a living sex doll vs. a guy who's truly into them, the girl, the individual. Doesn't matter whether it's about a one-nighter or a relationship: you gotta be into the girl you're approaching. This way there's very little acting involved and it's mostly about hiding your most glaring faults / craziness (although only in the beginning if it's going to be a long-term relationship). That's what makes it a double-edged sword, though: if you're into the girl, the rejection stings more. However, if she's also into you (much more likely if she senses genuine interest), the rewards are well worth all the rejections before that one 'yes.' I also think @Okon has a valid point: you learn to hang around women by hanging around women. There was a time in my youth when I had around two dozen pretty close friends (all purely platonic), only one of them male, and him I saw about once a year. During those years I learned a lot about the subtle differences between the ways men and women interact in social situations and it did help me come off a little less stupid than I otherwise would've when I eventually met my wife.
Not so sure all platonic responses translate into "not sexually attracted to you". Other reasons could be: 1. just got dumped after 4 years and am pretty bummed 2. just dumped a crazy psycho dude and am still shell-shocked 3. just moved here/ started school / new job 4. just lost a parent 5. you're a really nice guy but I'm pretty careful/shy/socially awkward, but you're a really nice guy... Call her. See how it goes.
Bigs hugs lewislewis. you sound like a nice sensitive guy. Now for a surprise... The only thing you need to take from rejection is this: She (or they)have let you know your not the one for her(or them) thats all. That says more about them than it does about you!!!!. I agree that there is no need for masks. Having wore one most of my life It dosen't work. so just be you and feel lovable.