I agree with Bob and Marcus.
Each of us, our friends as well, have our own strengths and weaknesses.
If he/she is not there for you in a reciprocal ways, perhaps he/she
has been/will be the 'go to' person in other areas during your times of need.
Definitely, it is a sign if you -- upon further reflection .... after the fact ....
are dealing with repercussions that affect your life/thoughts in a negative fashion
(beyond the "I can handle/I want to handle/it's okay" level) ---- definitely
it may be a sign/clue for you to re-evaluate the friendship.
Or at least be less available. It's good to offer any friend/acquaintance
support, but not if and when it is repetitive to the degree that it repletes you,
puts you in at least a 'psychological' half-empty mode. In this case, wait (or rather
''choose'' times to interact with your more needy friends when you are 'full'.
This ain't rude, it's necessary. Can't be there for friends/acquaintances or family
if one allows themselves to be drained/depleted/depressed to the overwhelmed degree.
@Dredd Said
But if it seems that every contact with you they, or at least the majority, they are producing more negative energy than positive and that you are having your positive energy sapped from you, regardless of what you do, is that then not a sign that maybe they wont change regardless of what you do. AND maybe you should re-evaluate the friendship?