Since we are required to emulate Hashem, it follows that we must also love the ger. Yet we are commanded to love the ger just as we are commanded to love Hashem. It understand this we must understand the Torah concept of love. The numerical value of love is the same as one.
Love is the product of unity between individuals, a recognition of a commonality and affinity.
In our relationship to Hashem this commonality is intrinsic, since we are created betzelem Elokim in G-d's image. Likewise, we share common responsibilities and goals with our fellow Jew. He is our re'ah peer in Torah and mitzvos. Parents and spouses, however, aside from the intrinsic commonality they share as Jews, may have nothing else in common. Of course we must work to develop and nurture an affinity and commonality in the latter relationships.