Is this breakup reason unreasonable?

So couple years ago this guy C. And I dated for 6 months. Then it abruptly ended bc he cheated on me and his way of telling me was sending me the proof and then cutting all contact without allowing me to ask questions. So time went by I moved on I dated other people. However once or twice a year I’d hear from him he’d check in see how I was and then abruptly leave me again.
Well now this last time he did that I asked him to tell me the truth and to stop blocking me re adding me and talk then leave and actually talk.

And so now for the past 4 months we’ve been talking a lot. And decided we’d try dating again but just taking things slow. But today he told me he plans on being in the military for the next 12+ years and hopes to be deployed many times. And I feel devastated, like this is a dealbreaker to me. I feel bad asking him not to because it’s what he wants it’s his dream. But I don’t know that I can handle the stress and worry of him leaving on deployment. Especially since he’s left and came back so many times in our relationship.

Am I being unreasonable?
Is this breakup reason unreasonable?
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