Subset and Superset

Back to school time, we study about the set, subset, superset and intersection thingy in mathematics.

I just realized this mathematics theory can be used to describe a relationship between two person.

Hubby told me, guy A (setA) likes girl B (setB)...But it is hard for the relationship to be happened if they have no "intersection" at all. As shown below:

Then I ask him, how about us? He told me, I am a "subset" of him, and he is a "superset" of me.

Subset means, 我有的他也有。。。

Superset means, 他有的我未必有。。。

How can this be true leh...?? Confusing...