네가 날 잊었을 리가 없어

The line, explained

Some sentences are not reports but refusals. When Korean speakers hear something they simply cannot accept, they reach for -(으)ㄹ 리가 없다: 'there's no way that…'. It is the grammar of denial, and K-dramas use it at their most dramatic moments, when a character is confronted with a truth too painful to believe. In today's line, someone stands in front of a person who no longer recognises them and insists it cannot be real.

네가 is 'you' as the subject, 너 plus 가, reshaped to 네가 so it does not sound like 내가 (I). Many speakers actually pronounce it 니가, so expect to hear both. 날 is the contracted form of 나를, 'me' as the object; lyrics and dialogue contract it almost every time. 잊었을 comes from 잊다, 'to forget', in the past tense 잊었-, with the future-and-guess modifier -을. The ㅆ links forward, so it sounds like i-jeo-sseul.

리 is the heart of the pattern. It is a bound noun, meaning it cannot stand alone, and it carries the idea of 'reason' or 'logical possibility'. 리가 없다 is then 'there is no possibility'. After the ㄹ of 잊었을, the ㄹ of 리 is pronounced as a clean l, giving i-jeo-sseul li-ga. 없어 is the casual form of 없다, 'there isn't'. Altogether: there is no possibility that you have forgotten me.

Notice the nuance. -(으)ㄹ 리가 없다 is about conviction, not evidence. The speaker is not saying 'I checked and you didn't forget'. They are saying 'I refuse to believe it'. Compare -지 않았을 거야 (you probably didn't forget), which is a guess. 리가 없어 is a wall. In speech the 가 often drops: 그럴 리 없어. And as a question it becomes incredulous: 네가 날 잊을 리가 있어? means 'how could you ever forget me?'.

Swap the verb and the drama changes genre: 네가 날 속였을 리가 없어 (you can't have lied to me), 네가 날 버렸을 리가 없어 (you can't have abandoned me), 네가 날 몰랐을 리가 없어 (you must have known me). The most common fixed phrase is 그럴 리가 없어, 'that can't be', which you will hear in thrillers, romances and everyday gossip alike. Once you know it, you will start hearing it every time a plot twist lands.