Being emotionally "reactive."

Have any of you heard the terms "reactive" to describe a person's emotions?
I use this word in my field of work and the best and most concise definition I can think of comes from Desert Alchemy -- and boy, does it it so aptly describe my experience.

emotional reactivity

1. involuntary and usually overly intense reaction to an external emotional stimulus, which often leads to feeling victimized by your emotions
2. an opportunity for repressed emotion to inform you of its existence

I am incredibly emotionally reactive in romantic relationships.

If I text you, and you don't text me back, I will flip-out.  My emotions will be out-of-control and feelings of hurt, helplessness, fear will erupt within me, even if it can't be seen by the human eye. Later, when he does respond, I will then burst into tears of relief, taking comfort in the fact that he's neither dead or gone missing, but that he's figuratively here and responding to me.  

That is the prime example of my reactivity and what I go through without fail with each partner.