Because the 6 and the 7 represent very two different people, with very different ideas, each number expresses love in a different way. This can lead this number pairing to form a somewhat of a love-hate relationship. 7s secretive and "aloof" nature, with the need for certain amount of distance, doesn't bode well with the 6s need for open expressions of love and emotions. This can cause a rift where the 6 feels insecure about the relationship, while the 7 experiences the 6s loving attention as an annoying disruption. Not all is lost, however, and as long as the two of you are able to recognize these differences, there is potential here.