She needs to replace negative thoughts with positive ones. It takes discipline and time. She shouldn't dwell on the past or future. Live in the moment. Figure out why she is the way she is. It could be something from her past that has traumatized her or you simply get on her nerves and she can't stand you. I don't know. Do some different activities or things that make her feel better about herself. Ask her what you can do for her.
It is better to live in a corner of the housetop than in a house shared with a quarrelsome wife.
This bit here is gold. Something ive been working on myself alot. The only peace of mind to be found is within yourself.