I'm an ESTP gal & relate to the lack of emotional responses. It takes a lot for me to care about keeping someone in my life. For most people, I don't give a crap. For others, I do.

However, I have emotional responses when it comes to people that I deeply care about, see a future with, and add value to my life. So losing them or breaking up definitely hurt me. I've had two breakups in the past that has taken me months to recover from. But I've also had a couple of breakups that I just never gave a shit about it & quickly moved on the next. Again, just depends on how much I care.

So yeah, it's quite normal to not give a shit if you really weren't that deeply interested in developing a long-term relationship with him. It's not just an ESTP thing to not give a shit about someone that you knew wasn't for you to begin with!