My ex-husband was 13.5 years older than me. In retrospect, it was a very bad idea to become involved with, and marry somebody that much older than me. I guess was kind of OK when he was 39 and I was 25 when we were dating. However, there were a lot of "generational" differences we had. We seemed to get along OK back then, but there were huge issues all the time that I should have paid attention to. Not even joking, I cannot count the amount of times (it happened so often) when we were out, people thought we were father/daughter instead of husband/wife. People would say something in regards to that, and then he would get all angry and crappy with me, and I literally did nothing wrong.
I guess the bigger issues began to arise years down the road. With that kind of an age difference, when I was late 30's, early 40's I was dealing with his "older person" issues. He never took care of himself (long story that won't be addressed here), so a lot of the problems were made worse due to that. Anyhoo, things just went from bad to worse.
Moral of the story I guess is, a big age gap can cause big problems.