We come th en to th e heart of the problem of marital confli ct. Personality defects and personality differentials are important only because th ey produce frustrations. But the bulk of marital frustrations are produced by very specific conflicts of interest which cannot be at - tributed to definite weaknesses of either person nor to degrees of similarity or differen ce between them. The partner's behavior, indeed, always pla ys a part in causation, but it is some specific phase of his beha vior in relation to some wish of his partner which in other situations might produce no trouble. It is often a phase of his· behavior which would not easily be noted before marriage as a danger. Both partners at first ma y be well adjusted to life in general, but th ey may develop maladjustments to each other which then spr ead to wider spheres.