Every relationship (including the "best" ones) have their ups and downs, but there are certain things that make some relationships totally unbearable.
That doesn't mean you should quit at the tinniest hint of trouble, because some problems can still be salvaged.
However, if you're experiencing any of the following issues, then perhaps you could be spending your time with the wrong person.
Find someone who treats you like you need to be treated and makes you happy. Someone who makes you feel good about yourself, and whom the people you trust encourage you to be with.
If these words don't describe the person you're with right now, then it's time for you to consider taking a walk!