Trying to convey another person's thoughts and feelings through a translation is difficult, especially in poetry.
However the following is my interpretation of the sentence, "Love, without you I'm just a person."
사랑아, 네가 없이는 나는 그저 사람일 뿐이다
I chose to emphasize "just a person" with (으)ㄹ 뿐이다 which indicates only one available course of ...
When 있어서 is used as an idiom for "when it comes to" or "as it relates to", its full form is -에 있어서(는) and it should be followed by some descriptive statement, not 안 되다.
V-아/어서는 안 되다 may be considered another idiom which is equivalent to V-(으)면 안 되다 ([you/they/it] V-ing will not do => [you/they/it] should not V).
는 in this case is an ...