A slight issue

My girlfriend and I are very much in love. However, from January to August last year we had a lot of trouble. We got over it, and are doing much better now.

I am planning to retire this year, in September, and we are in discussions about moving in together. She is worried that her love for me will get stale and she won't want to see me. I know myself well enough that I will always love her. But last year made me worry a bit, most of the problem was her insomnia, some of it was fear. What if she goes through that again when we are living together? I am hoping that we will do well together all this year, but I am not certain of that.

I am an old romantic, and spent 30 years in a wonderful marriage. She spent 12 years in a very uncomfortable and bad marriage and now has a bad opinion of it. What can I do?