Where does it say the op doesn’t initiate contact? I can’t see that bit 
I’m surprised by the responses you’re getting. It’s totally normal for adults with busy lives to have periods where they see less of their friends. That doesn’t mean they’re users.
If someone has been low for a while and has been depending heavily on a friend, clearly that’s hopefully going to be temporary. Why would anyone expect (or want) that level of neediness/contact to continue?
And if your friend feels hurt at not being needed so much, acting out with short answers and ‘dropped’ notes while not accepting reassurance seems like a terrible way of dealing with it.
Like a PP, I’ve encountered friendships where one person really thrives on being needed - it fills a need in them too - and becomes resentful when the person who they’ve been supporting gets into a better and happier place mentally. (I was a third party in this situation, so I’m not particularly coming at it from a biased position.) It was an unhealthy dynamic and because of that, it just wasn’t a sustainable friendship over the long term.
I wouldn’t have thought to call either of those friends a user, but if anything, looking back on it now, I would say it was the “supporting” friend who was almost using the other - depending on her to feel needed and important, and almost wanting her to stay sad and lost in order to maintain that position. Friendships are complicated and need to be flexible.