決心がつかない

can't make up one's mind

→ 決心
phrase Rare #36,736
can't make up one's mind Used when someone is unable to reach a decision. The affirmative form 決心がつく means to make up one's mind or reach a decision.
JA: どの大学に進学するか、まだ決心がつかない。
EN: I still can't decide which university to attend.

どうしても決心がつかないんだ

I just can't make up my mind.

彼女は結婚しようと思う決心がつかない

She is considering getting married, but can't make up her mind.

行くべきかどうか決心がつかない

I can’t decide whether I should go.