Negativity vs. Positivity Or Positivity VS. Negativity....You decide :)

Maybe instead of looking at his faults I should be looking at all of the positive things he does.  I am always talking about looking at the positives rather than the negatives of every situation.  And yet, I continue to look at everything that ticks me off about him or what he doesn't do that he says he is going to do.  Those characteristics are what makes up his personality, and I know that I am by no means perfect, so why do I want him to be exactly like me or believe everything that I believe.  I am making everything so difficult for him.  How do I change my behavior? Hopefully by becoming aware.
I also have another hypothesis about why things are the way they are right now.  Could it be that I am this way because of school?  I am always in such a bad mood and stressed, but the winter break is coming up.  There is time to test this hypothesis of mine, and I plan on doing just that.