Having a good attitude is an essential skill to be learned, especially in a relationship. I know it sounds like a simple skill to master, but it takes determination and intention. You can either chose to become great at having a bad attitude or chose to become great at having a good attitude. I personally have learned through the years it takes practice to master the skill of positive thinking and having a good attitude.
There are some great tools I have used that have helped me "fine tune" my attitude. I try to listen to personal growth audios everyday. Programming your mind for success is essential in maintaining a positive attitude. As you go about your day, it's obvious that we encounter many negative factors. Listening to positive messages can help counteract all of the negative energy that will try to pull you down. There are so many wonderful self-help audios for you to take advantage of listening to!
I know that being a women means lots of different emotions and "mood swings." I am sure that your man knows when to cut you a little bit of slack. The important thing to remember is that you are attempting to become the best version of you. So keep on pursuing the things in life that will make you better!