Summary You aren't on your purpose.

Body So you just got dumped by a girl? Or maybe you're after this girl but sadly she doesn't really reciprocate the feeling. You know what I'm on about. We've all been there at one point, have we not?

Great nice one jackass, you just described textbook one-itis. What are you going to tell me? Spin plates, muh abundance mindset?

Although good advice, I am not here to tell you this. I've come to a realisation. One-itis is cured by spinning plates and abundance, but that's just a band-aid to the true problem at hand. You have one-itis because you don't have a purpose. Now I understand I probably sound like a complete hippie right now. But here me out.

Why lack of purpose/direction leads to one-itis

As humans we all have a direction/purpose. I'm not talking about one big life direction, I'm talking about short-term daily goals. You've got one-itis because you don't have those short-term goals. The long-term goals are very hard and tiring to achieve. So you go back on to your one-itis goal. YOUR SHORT-TERM GOALS ARE BEING REPLACED WITH YOUR DESIRE TO GET WITH THAT GIRL. AS THE DAYS GO ON THIS ACCUMULATES LEADING INTO A LONG-TERM GOAL. HENCE ONE-ITIS IS BORN

Ok great I lack direction in life - any tips? Well the first and most useful tip I'd give is setting daily achievable goals. These goals should be on self-improvement and focusing on yourself. You must become the centre of your universe. When you can reach the point where you are more focused on the task at hand rather than the girl. That's when you know you are on your purpose.

So what Lifetopic. Just distract myself?

No. I tried that before. I tried distracting myself. It doesn't work. Distractions give short-term pleasure and no long-term pleasure/happiness. Doing weed and drinking with my friends was pretty fun, but at the end I'd feel terrible. I just wasted a day for a useless activity. I didn't make any progress. I didn't improve myself. Made no long-term progress, only had some short-term fun. I wasn't on my purpose. Your short-term goals should fit with your long-term goal.

Example :- My current long-term goal is to be able to bench 100kg. My short-term goal is to hit the gym 3/4 times a week. My even shorter-term goal is to get the correct amount of protein in my diet for that day.

Breaking your goals down into shorter, and shorter goals puts you on your purpose. You can make multiple long-term goals. Example mine is to get my shit together this summer. So I had made a list of goals. And thought of ways to achieve them. Being on my purpose makes me less likely to pine over a girl.

TL;DR Make long-term goals, break them down into smaller parts. Eventually you become fixated on achieving these goals, and as a result you become the centre of your universe.