In my early twenties: for all the friends I had, for all the state to state traveling we did for raves from 1998 to 2001 or so, for all the parties I had in my parents basement with 10 to 15 people chilling at my place - three days out of the week in the summer; I had nothing to show for it on the relationship level. I could go to a party, roll in deep, be the guy everyone seemed to know, and... that was about it.
For as much as I've tried to refine my own social skills I had to face some hard realities; the thing that keeps me out of the box on dating is unchangeable. That said though at almost 32 and single I wouldn't trade places with you for anything. In your early 20's the pressures you put on yourself are insane, even if you decide to say screw it and focus on other things your friends won't let you go on it and - under the weight of other people's criticisms, you feel like you need to keep reinventing the wheel and keep reproving to as many new people who come your way and challenge you on what they don't believe you've already done. It seems like it takes until your late 20's that people get over it, actually understand that they themselves have things in their own identities that they can't change, and if someone's constantly single they aren't either harping on them about it or diagnosing them as a closet homosexual and then trying to test them and prod them out.
The only thing I can say is hang in there and, more important than anything: do something about your grades. The workouts are great but do them for yourself. Build skills, work on refining talents and abilities (especially marketable ones) and truth be told, singlehood has a very big plus - you keep as much of your own money as you want, you have far fewer people spending your money for you with nearly the intensity, and you have so much time to invest back into yourself - if trying to get in to the relationship world is like trying to break down a tank with a toothpick, I hate to say it but, it sounds like you need to shift your priorities. I think the depression will start to fade more once you have most of the illusions and smoke people have blown up your arse about what life is or should be out of your system and when you realize that next to no one is living the dream.
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The loneliest part of life: it's not just that no one is on your cloud, few can even see your cloud.