I seem to have this really negative attitude, I always seem that there is an obstacle in my way or there is something wrong and I can't seem to handle it then I lash out.

I always have an issue with being left alone for long periods, I start to over think things in a negative way, it is now starting to affect my relationship, he does extra activities after work and on the weekend and I seem to think the worst, i.e he doesn't want to spend time with me, or that he is off with me,

I have tried to keep myself busy, reading, painting etc, but I can't seem to shake it off!

I want to know what I can do to shake this mood off and how to stop it earlier on rather then letting it manifest itself.