How do I fix a relationship that is falling apart?

tell him/her you love him/her and ask for forgiveness or bring gifts or get him/her somewhere to talk it out and leave it behind you and live happily ever after(: (: (: (:

Talk about the relationship and work at the relationship.
Firstly, both people have to decide if the relationship is worth saving. If one person or both don't think the relationship is worth saving, then any further attempts at fixing the relationship will be half-hearted, and probably won't work.
Secondly, you have to figure out what the problems are in the relationship. Often the surface problems are really deeper problems, like lack of commitment, overall laziness or complacency, etc.
Next, both parties have to agree to work at these problems and actually follow through. Relationships aren't magically fixed; it takes a lot of hard and consistent work.
Charlie Sheen.