-느라고

-느라고 means 'because I was busy doing A', and the second clause is usually a negative result: couldn't do something, was tired, was late.

이유·원인Reason & cause

Han: Rain isn't something you were busy doing; for outside causes use -아/어서.

Examples

이사 준비를 하느라고 정말 바빴어요.I was really busy getting ready to move.

게임을 하느라고 약속 시간을 잊어버렸어요.I was playing a game and forgot the time of our appointment.

숙제하느라고 어젯밤에 못 잤어요.I couldn't sleep last night because I was doing homework.

-느라고vs-아/어서-아/어서 gives any reason, including weather or traffic (길이 막혀서 늦었어요); -느라고 is only 'because I was busy doing something': 화장하느라고 늦었어요.

V+느라고

준비하다 → 준비하느라고, 놀다 → 노느라고

Only verbs (an activity that takes time), never adjectives.
Both clauses have the same subject, and no past tense goes before 느라고 (not 했느라고).
The second clause can't be a command or suggestion.

Wrong: ~~비가 오느라고 늦었어요.~~

Right: 비가 와서 늦었어요.

Rain isn't something you were busy doing; for outside causes use -아/어서.

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