Then do something to fix it. You can waste years of your life, coasting in a relationship. Go to counseling, read a book on improving relationships or just do try to mix things up in the relationship. This will help you get out of the rut. If the relationship can not be work out, then move on.
Life is too short to be in unhappy relationship.
Remember no relationship is perfect. There will always be some problems regardless of which you are dating. It is just a matter if you can deal with those problems or not. There may be come a time when you have dated a lot and have not found the person you are looking for. If you have been dating a lot, it is easy to become burnout.