What keeps our heart from expressing pure lovingkindness? Understanding "tanna" or clinging, that gives rise to attachment & aversion, is the obstacle.
Contracting around either the comfortable or uncomfortable aspects of life will inevitably cause conflict. The resolution of that conflict is the Buddha's teaching.
On this Path, there is release, and there is also awakening into something vaster. Wherever suffering occurs, that’s the place of release. Apply yourself to the restricted places, and effortlessly, the revelation arises.