godan verb (-ru)
harp on a subject; dwell on something too long
Slang; used when someone keeps talking about the same topic or repeating the same point excessively, often to the annoyance of others.
もうその話はさだはるなよ。
Stop harping on that story already.
彼は失敗をいつまでもさだはっている。
He keeps dwelling on his failure forever.