discussion / dialogue / conversation / negotiation

(literary) they

consultation, talk, talking something over

many years

(used with negatives) for a long time

many years / a long lifespan

vendetta (bitter, destructive feud in which each injury is revenged) / discord

feud / be at odds

solution, settlement / (music) Progression from dissonance to consonance; a chord to which such progression is made; resolution

(transitive) solve, resolve, settle (a problem, a trouble, a criminal case) / (intransitive) be solved, be settled / (intransitive) can be solved; be soluble