First. let me say that I commend you for your forthrightness. Not many have that kind of courage, particularly, given the tough crowd that dwells within this site.
You have already stated your problem. I think you already know what the solution is, you are just having problem implementing the solution.
Problem: Basing happiness on something other than yourself.
Symptoms: Going through the motions with girls, but follow through is sucking hind tit.
Other facets of your life are also lacking robust qualities.
Slight depression, Lethargy, etc.
When someone I know goes through what you describe, the first question I ask is if there has been any significant change in your life.
Diet? Recent move? New School? New Job? Stress can attribute to many of these problems.
My sister is in the same boat. She complains that she doesn't have any friends, no life, but she's too damn lazy to get out of the house and be a friend to someone. I tell her to find a hobby, take a class and she tells me it's too much trouble. So, I just tell her to stop complaining. She knows the solution, she just doesn't want to work that hard.
Perhaps your case is different. I can't say.
Now, let me say this.
"What do I do next?" But the answer just isn't there. I don't have it. So I make it up from one day to the next based on what other people do.
Since you claim that you don't know what to do next, Big Pappy will tell you. Breathe in, breathe out. Live. I don't mean to just go to work just for a paycheck.
Ask yourself what you really like to do. Maybe nothing. I see it all the time. People just going through the motions, forgetting that life is what you make of it.
Have you ever known the sun to shine everyday? Somedays are gloomy. Some days life is not very much fun. Sunshine after rain, laughter after pain.
But, I can promise you this. Life can get better. a LOT better!
Think of it as a cyber slap in the face, telling you to snap out of it.
Noone can get you out of this funk except you. YOU decide how you feel!
You might tell me that you're "depressed" and I would say "Nonsense!"
You can decide how you want to feel!
You want to say "Woe is me, I've fallen into the pit of despair.",
I'm just going to throw you a well-anchored rope. You can pull yourself out anytime you wish. All you have to do is stand up, dust your keester off and live!
How do I do this?, you may ask.
Right now! Do something that you have never, ever done before.
Go to a grocery store, find the hottest lady you can and take something out of her buggy. It's not hers yet, she hasn't paid for it. You're not doing this for any other reason than you've never done it before.
Feels kind of weird doing something screwy like that? SO WHAT!
Your life is not a goldfish bowl; your only limit is your imagination!
You can do whatever you want, as long as it doesn't hurt anyone else.
No limits, no fear!
If you haven't had a vaction in a couple of years, take one soon!