Chemical Reaction

If you have studied Chemistry before, you will have come to realisation that when two things are mix together, some of them may produce chemical reaction and some of them are not. Hanging out with different group of friends could have different type of feelings. Some make you smile, some make you cry, some make you think, and some make you angry.. When you blend them together, you got your colourful life!
However, there is also some people you could never get along with because there is no reaction between two of you. In lay man term, no 'click'. you cant just click and be together. You tried hard, you put in so much effort to make it work, but sorry baby, it just doesn't work. Then why still insist? try others, you will find different sparks and probably you will live happier.
Some reactions are unique, unique means it belongs to two of you, others won't be able to understand what's going on between the eye sight, the action, and the mouth. Some reactions are common, everyone could laugh together and get the meaning within a second.
I am looking for some extra thing between us -- a little bit of sparks to lighten up our world. Probably the life pressure and the obligation had deter us from doing something sweet. I am confused, is the suppressing you, or we are not meant to be together. We get along well, but it doesn't produce spark.
I am contemplating what should I do right now, to hold on or to give up? I chose to let it be at the end, because I have no idea what to do, I guess I can only follow the flow, I will take whatever comes to me.