my sweet, uncertain and painful happiness

I sent u a postcard in Stansted Airport just before leaving, wishing that u might think of me some time. The postcard might can remind u at least.
The fact is u seemed to receive the card the second day I leave and u sent me a text message.

I try to find how u feel and what u feel, but it seems not easy for me to figure out. This makes me feel sad and painful...
I am sufferring in the happiness u give me. When I think about u, I dont know whether I should be happy or feel sorrow. If this is ur way,... I try to persuade myself by thinking this way. However, even a just met new friend shows more concern of me than u do...

Do u know how happy I was when I received ur text last night??