This pattern expresses that one had intended to do something but instead one's mind has changed due unfavorable circumstances.

- is a contracted form of (으)려 하다가
- is only used with action verbs
- the final clause this pattern connects to is usually in the past tense
- both clauses must have the same subject
- 려다가 affixes to verbs ending in a vowel
- 으려다가 affixes to verbs ending in a consonant

Examples:
일본어를 공부하려고 하다가 한국어를 공부했어요./I was going to study Japanese but I studied Korean.
잠을 자려고 하다가 새벽까지 영화를 보기로 했어요./I was intending to sleep, but I decided to watch movies until dawn.