I'm not Korean but I hope I can help! 한다 is like... a conjugation in the narrative present tense. Originally it is 하 +는다 = 한다. It's not particularly used to people older than you. Therefore 사랑한다 - I love you (now). (lit. love do-now) - to someone your age or younger And 사랑해요 - I love you. (lit. Love do) - politely Virtually they mean the same thing.