I do the same thing
23.10.2014 by Dayton
I started doing this as the relationship was spoiling a bit and now that we aren't together it has gotten worse. Sometimes I could see it as just not being interested. Other times it is really just that I shut down. I have no explanations and just say "I don't know". Which, makes the situation worse...but I really just have no emotions or feelings to share.
Same here
23.11.2014 by Baylia
I do this too, although I think this is more to do with using dissociation to protect yourself, rather than alexithymia.