How to not be nervous?

I have been in a lot of bad relationships over the years where I was used and mistreated. Now due to all this and several times being very badly hurt emotionally. Now I feel like I am walking on eggshells a lot and feel like she is wanting to leave me. I know to some extent that she doesn't but I also don't want to put cracks into a foundation by putting things there that aren't. Any tips on how to work on this. I care for her deeply and don't want this to end, just small things come up and my mind shifts to she's wanting to leave me ie not getting dinner tonight, her being cynical, asking to tone down the romance etc. Any tips?