네가 있기에 난 오늘도 노래해

The line, explained

Fan songs are a genre of their own in K-pop: tracks a group writes for the people who have stood by them, usually played near the end of a concert while the lightsticks sway. They need grammar that can carry gratitude without sounding casual. Today's line is that kind of chorus, and its key ending, -기에, is a "because" with a bow attached. "Because you are here, I sing again today." In plain speech it might sound like too much. In a song it sounds exactly right.

네가 is 너, "you", with the subject marker 가, usually sung as 니가. 있기에 is 있다, "to be there, to exist", plus -기에. So 네가 있기에 is "because you are here". The beauty of 있다 is its range: it can mean you are in the room, you are alive, or you simply exist in the singer's world, and a fan song wants all three at once. The double ㅆ in 있 closes into a stopped t sound, and the ㄱ after it comes out tense.

난 is 나, "I", fused with the topic marker 는. 오늘도 is 오늘, "today", plus 도, "also, again": "today as well, still, once more". That 도 quietly implies yesterday and the day before. 노래해 is 노래하다, "to sing", in the casual present. The full line: "Because you exist, I sing today too." Notice the result clause is a plain statement of fact. -기에 is happiest leading into something that simply is, not into a command or an invitation.

Compare three ways to say "because". -아서/-어서 is the neutral everyday one: 네가 있어서 좋아, "I'm glad you're here". -(으)니까 is spoken and often persuasive: 네가 있으니까 괜찮아, "it's okay, since you're here". -기에 is the literary one, found in lyrics, speeches and letters. Its spoken cousin -길래, which has its own lesson, reacts to something you observed. -기에 cannot be followed by a command, so 비가 오기에 우산 가져가 sounds wrong; use -(으)니까 there.

Swap the reason and keep the gratitude: 네가 웃기에 (because you smile), 기다리기에 (because you wait for me), 듣기에 (because you listen), 곁에 있기에 (because you're by my side). 듣다 is a ㄷ-irregular verb, but -기에 starts with a consonant, so the stem stays 듣. The ending works in the past too: 네가 있었기에, "because you were there", which is exactly the phrase you would write in a farewell letter or say in an acceptance speech.