思おもいあぐねる

ichidan verb, transitive verb

rack one's brains in vain; mull over endlessly; be unable to decide

Describes thinking hard about something but getting stuck, unable to reach a conclusion or solution. Often implies frustration or mental exhaustion.

• 何なん度ども考かんがえたが、いい案あんが浮うかばず思おもいあぐねている。

  I've thought about it many times, but no good idea comes to mind and I'm racking my brains in vain.

• 進しん路ろのことで思おもいあぐねて、夜よるも眠ねむれなかった。

  I mulled over my career path endlessly and couldn't sleep at night.