やがて彼女はそれを後悔するだろう。

before long; soon; almost; nearly; finally; in the end; eventually

she; her; her; girlfriend; sweetheart

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

that (indicating an item or person near the listener, the action of the listener, or something on their mind); it; that time; then; there (indicating a place near the listener); you

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

regret; repentance; remorse

be; is; indicates past or completed action; indicates light imperative