We had one period a long time ago when I told him that I wanted to take some time off. That I didn't like who I was in the relationship and that I wanted some time to think and to clarify in my mind. But he kept contacting me throughout that time, and eventually I simply fell back into the relationship. At the same time, I probably wasn't devoting enough of my energies to focusing on the questions and concerns in my mind.
We really haven't had any relationship problems because 1) we get along well, and 2) we both tend to avoid emotional confrontations. But communicating about deep things has not ever been our strongest suit either.
I think the initial trigger was another man. That was a long time ago, but it definitely made me think that I wanted more. That I wanted someone who was looking for more adventure. Who likes to do more of the activities that I'm interested in. Who is handier. Who, on their own, without prompting, would be more likely to help out with house chores (he doesn't really cook or clean, and I didn't ever want to be the housekeeper).
I've been in a few other relationships. One was particularly emotionally draining. It went on for two years. There was one other two year relationship between that one and my current relationship.
One other thing that has held me close to this relationship is that he has been willing to give up/change his wants and desires to allign with mine. For example, I know that he wanted children in the past. I always said I didn't, because of the "partner" issue (I could see him taking on the role of the bread winner and I would be the lawyers wife, keeping the house, raising the kids, and being the foundation of the household. And I didn't want to have to carry that alone.) But I've also pulled away from any intimacy with him, too. I'm just much colder to him in our intimate life, and he simply perseveres.
I think in many ways he just thinks he can wait me out and I'll come around.