Love Grows Through Giving
Ahavas Yisroel
Rav Boruch explained that love is acquired through deeds. Each gift a person gives his friend is like a bullet that pierces a hole in the friend's heart, even if that heart is as hard as stone. From the many holes a space opens, and the love of the giver enters it, drawing out the sparks of love in the friend. From the two loves a garment of love is woven that covers them both.
Source: Dargot HaSulam, vol. 1, essay 776