We have two WFE servers and Application server for the SharePoint. User profile service is configured and we want use it. But User Profile Synchronization Service stays on starting state and after a while stops, then it makes the forefront identity manager services disabled too.
I just checked the farm user account access and also configure the service again and again to fix this issue.
The stuck on starting issue can be a real pain to deal with. Spencer Harbar wrote an article a few years ago that I, unfortunately, have to refer to from time to time. It's very comprehensive and there are several things that could cause the problem but it usually comes down to incorrect permissions on either a windows service, a SharePoint service, a DB, or issues in forefront. Bookmark this one... it will be your friend :)