What are they?
Relationship issues are many. There is not one, single relationship issue in any relationship, like “he is wrong and I am right” or vice-versa. Rather, relationship issues are complex. They come out of the interaction between two or more persons. What is the most important thing to remember about relationship issues? Simply this, that all of life: your job, your career, your partner, your parents, your children, your coworkers are based around interaction(s) with you. And therefore you are in a relationship with many, many people.
What causes them?
What causes the relationship issue(s). Again, there are many, many different and diverse reasons. Each one is dependent upon the type of relationship you have with that person. Obviously you will have a different type of relationship from your boss than your coworker or employee. And that relationship will be different again from the one with your partner (wife/husband/boyfriend/girlfriend) or your parents or your children. However, at the core of most relationship issue(s) is a clash between values, desires and needs. What you want is maybe not what your boss wants, or your husband or your mother-in-law or your granddaughter, etc.
What fixes it?
Most counsellors or psychotherapist don’t talk about “fixing” or “curing” clients or patients. Clients and patients are not automobiles nor hams. It is not as simple as that and people are not machines. Rather we talk about what can help the client to function better and alleviate their distress. With regards to relationship issues, by examining what your values are and the other person(s), hopefully some common ground can be found. Moreover, everyone in a relationship, where there is a relationship issue, sees the relationship from their own values and standpoint and usually not the other person’s. It is the examination of this interplay which helps to lead to a health(ier) relationship.