to tire of; to lose interest in; to be too much for one; to find unmanageable; to be beyond one's control; to not know what to do with
返事に困ってあぐねている。
I'm at a loss for a reply.
この問題の解き方にあぐねた。
I was stumped by how to solve this problem.
返答にあぐねて、彼はしばらく黙り込んだ。
Unable to find a reply, he fell silent for a while.