Lines 

Hyun-ju : 당분간 나 백수된 거 엄마아빠한텐 비밀이다. 알면 바로 결혼 압박 들어온다. 

Don’t tell mom and dad that I’m not working. Once they find out they’ll pressure me about marriage.

Do-kyum : 결혼이 그렇게 싫어?

사실 나 5년 전에 그 남자랑 누나 결혼할 줄 알았어.

You really hate the thought of marriage that much?

I really thought you would marry that man five years ago.

Hyun-ju : 아... 그 때...

Oh… back then…

Do-kyum : 말 나온 김에 물어봐도 돼? 왜 헤어진 건지.

Since we’re on the subject can I ask you why you broke up? 

Expression of the Week

물어봐도 돼? -- can I ask you (something)?

물어보다 – to ask; inquire; interrogate 

Casual – 물어봐도 돼?

Semi-polite/polite – 여쭤봐도 돼요?

>>The verb “물어보다” + “~해도 돼” turns the verb into the question form “can (I) ask (you) something”. In the dialogue’s case what Do-kyum wants to ask is why Hyun-ju broke up.

>>The polite form of “물어보다” or “to ask” is “여쭤보다” which would be used when speaking to elders or strangers.