"널 사랑할 수 밖에 안되요" is not correct in its construction. We usually say "X 씨를 사랑할 수밖에 없어요" or 당신을 사랑하지 않을 수 없어요 (we don't say 너 except to a friend). It means "I can't help loving you", like "I end up loving you even if I try not to". There is also the "-지 않으면 안 돼요" form, but it means "I have to do something", not fitting in your sentence. And here's a line from an English song with a similar phrase. Wise men say only fools rush in..............현자는 바보들만이 달려든다지만 But I can't help falling in love with you....난 당신을 사랑하지 않을 수 없어요