Karma is complicated and mysterious, to the point we rarely understand exactly what we have done to be in difficult situations that occur in our lives.
In trying to understand how karma influences the way love works in our lives, it is helpful to look at love as a higher concept that also has a human form we have a relationship with.
Whatever we are experiencing in the present moment is both the fruition of our previous karma and the planting of seeds for future karma.
Buddhism has no single dogmatic view of karma. Unlike Western religious traditions, Buddhism is extremely fluid in its teaching, and assumes that people will gradually move towards more sophisticated understanding of the truth.