expression
mutual consolation after shared hardship; licking each other's wounds
Idiomatic expression describing people who have suffered similar difficulties comforting and supporting each other. Often carries a slightly negative nuance of wallowing in shared misery or reinforcing each other's victim mentality.
失恋した者同士で傷の舐め合いをしても、前に進めないよ。
Even if we console each other over our broken hearts, we won't be able to move forward.
あの二人はいつも会社の愚痴を言い合って、傷の舐め合いをしている。
Those two are always complaining about work and licking each other's wounds.
慰め合う is a more general term for comforting each other, without the specific nuance of shared hardship or the slightly negative connotation of wallowing in misery.
Literally 'licking each other's wounds', from 傷 (wound) + の + 舐め合い (mutual licking). The figurative meaning is a direct extension of the literal image.