How can I forget my old girlfriend? Hello to all of you and thank you for your time in answering the questions here.
I have a big problem with my feelings. I have a huge emotional lack, which means I've never moved on with my old girlfriends. My last three girlfriends, two that I loved a little bit, and one with whom I had a long relationship and thought she was my soul mate.
As a result, I suffer and often come back to them again and again and again and again... in a never-ending loop. I look needy and pathetic.

How can I get better, please?

Thank you very much.
As my teacher explained, the reason we are needy and clingy is because we have not discovered how to be our own source of "energy". We are like babies depending on mothers' tits for nutrition, in this case emotional/psychosomatic nutrition.

In order to become independent, we must learn to obtain energy by ourselves. The entire Buddhist path can be seen as a method for gaining complete independence from external circumstances as far as energy. Once we learn to be completely independent, we are free (call that Enlightenment, Nirvana or anything you want).

In order to understand energy we must understand the principle of this/that conditionality and 2nd/3rd Noble Truths. In brief summary: when "is" and "should" match, we feel gratified, we gain energy. When "is" and "should" mismatch, we feel miserable, we lose energy. When we clearly see this principle at work in our own lives we can extract all kinds of tricks from it.

Famous Buddhist trick is to let go of "should" (aka attachment) in order to liberate oneself from the mismatch and thereby cease suffering. A more advanced trick is to transcend any and all "is" and thereby make oneself immune to any future suffering.

But there is other side to this equation, and it involves taking advantage of matching "is" and "should" in a positive way. If you frame your goals and values, and your achievements in such way that "is" and "should" match, you can extract energy from the same mechanism that normally generates suffering. Buddha described it gloriously in many suttas on Jhanas.

In fact, generation of energy is one of the most important practices in Buddhism, but not all practitioners realize that. And how do we generate energy? We generate it by setting up clear criteria for success, achieving them, and congratulating ourselves on the achievement.

Traditionally in Buddhism this is practiced as Sila. We vow to uphold the precepts, then we uphold them, then we examine ourselves, congratulate ourselves, and extract energy from the achievement, energy we can then reinvest back into practice. But it does not have to stop with Sila. Every and all action can be a source of energy. Starting with simple daily tasks. We can set our own standards of perfection for tidiness and cleanness in our household. Then we can slowdown and put some determination into implementing our standards. Then we can observe ourselves having achieved it, congratulate and extract energy. Makes sense?

This works even at the level of day to day actions. If we set our own standards for dressing comfortably and looking the way we want, and then stay true to our own standards every time we dress, the daily ritual of dressing becomes a source of energy.

In general, being consistently perfect by your own standards minute after minute, hour after hour every day - is an incredible source of energy. It is a nuclear station we always carry with us.

Achieving this level of satisfaction requires developing a perfect connection with ourselves. We must be in deep touch with our inner core, with our true nature, so we can always stay true to ourselves, never rushing, never compromising with our truth.

When we are like this, we don't depend on any external source of energy, we don't even depend on favorable circumstances anymore, and not even on success. We get a kick from the very process of knowing that we always stay true to ourselves and always do our (optimum) best, given the multifactor/multidimmensional limitations of the circumstances.

This in itself is a path to Enlightenment, if you follow it through to the very end. But it can also serve more mundane purpose, like making you free from dependency on a girlfriend. Dharma is a very powerful tool when one puts it to actual use. 

Good luck with your problem and let us know if you have further questions.