Relationship Insecurity

You say that relationships are what make us happy and I completely agree. But what if a relationship does not go the way we want to despite of putting all our heart and good intention on it. The problem is with this guy I got to know recently. It was an immediate connection and jokingly we called each other’s soul mates. There was a lot of similarity in the way of thinking and he also had a very positive outlook on life, just like me. However he started to have less attention on me somehow and more on his works and different projects. It got so intense that part that he decided to just stop the contact. He says that it is because of work only, and that he is still interested on me. He hopes that we can be together some day but not now. Thinking of your lessons of wisdom, I try to let go, and leave up to the Universe to decide the best. But it is not easy. Time by time there is the urge to write and be in contact, but i have promised not to do that. I experience true joy every time I think of him, but I feel that is not enough. Do you have any advice on how to handle this in the right way? I am usually a very happy and active person and always try to see opportunities instead of problems….but I would still appreciate some of your wisdom on how to see the opportunity on this specific issue.