Young Writers Society

you want something from me and that something is something that I lack
You do use 'something' a lot in here, but I think you should just add after 'me.' I liked the repetition of 'something' but the sentence was a little awkward.

I don't know what to do
because when I see you with someone else I want you
Rhythm is a little off here and I didn't particularly like the wording of this part.

our relationship can be summed up into one word:
convenience.
This seemed a little blunt. Try making it flow better with the rest of the poem.

it's easy to leave you when I know you would come back fast
But I feel bad
This part, too, needs to flow better with the poem.

all I know now is convenience.
Maybe you could take out 'now' to keep with the other line and to take out unnecessary words. But this is a very nice last line.

This was better than I expected it to be [don't worry- that's a compliment ]. It was a straightforward poem and easy to relate to. Some parts I didn't really like, but overall it was pretty good.

Only one problem;

you want something from me and that something is something that I lack