I'm 23 now, and have never had anything develop into a proper relationship, mind you there's only really been two opportunities, both of which were somewhat doomed from the get-go due to her circumstances; they each lasted about a week or two, lol. It was only a year and a half ago that I lost my virginity (aged 21), and have only had sex with one other women since. I don't give myself that many opportunities to meet or pursue women, and having a stutter lowers my self confidence in that respect. I'm decent looking, intelligent, 6' tall, fairly athletic build in relatively good fitness, muscular, around the 12-13% body fat range. Everyone thinks I'm a nice guy, but I guess it's the lack of confidence and social anxieties that are working against me.
I recently met a girl who seemed to fall for me pretty heavily, only to have her re-assess everything a week later (to her/my defence, she had experienced a recent tragedy, plus is leaving town very soon), etc. Like some others have mentioned, in hindsight I was probably way too excited due to my lack of experience. I probably came across as being too eager which probably freaked her out a little. Who knows, but it's definitely one of things us guys with little experience under our belt have to be aware of.
I've also learnt that it's generally best to suppress your nervousness and to not be so transparent around women you're getting to know beyond just friends. My strategy for dealing with this is usually telling them how nervous I am, asking for kisses, etc, which really is not very attractive behaviour. I feel I'm learning pretty quick, just really want to get a bit of experience under my belt so meeting someone isn't such a damn novelty.
I use to be pretty comfortable without ever having had a relationship, as I generally enjoy my space and can keep myself entertained, but as I get a taste for women/relationships and get older, it feels like I'm missing out on a whole other dimension to life.
It all serves as motivation to stay fit and healthy, work on my insecurities, work on my cock length (6" NBP, 5.5" girth) and stop looking at porn, even the soft-core stuff. I need all the libido I can get.
Just me two cents. Chin up.