I think they're gonna get back together in season 3, given where I think they're going with the story.
Admittedly, this does bring up a big problem with the long gaps between one season and the next, for all these shows: they end the season with things unresolved. Then, they make you wait, sometimes as long as a year or more in real time, before you'll get to see the character again, and the new season always skips ahead over several months of in-show time instead of picking up where the last one left off. This means that we miss out on a lot of good, interesting stuff that must have happened during the gap, which we just never get to see, and its frustrating. (Another example of something we missed out on was, what sort of legal chicanery did Foggy do to get Luke Cage out of jail at the start of The Defenders?)
But obviously, seeing the rest of the reveal conversation was never going to be done in The Defenders, because that show revolved around an event that took place over the span of about three or four days, and they had a huge cast of leads and supporting characters to juggle. Not to mention that the writers may have thought doing a reveal scene for Karen would become repetitive and redundant; that it would basically be a rehash of "Nelson v. Murdock" just with Karen in place of Foggy.
All I hope is that maybe, the writers will cover Matt and Karens discussions as flashbacks in Daredevil season three. Mention them in The Defenders (check that off), now show what happened once theres time for it (aka, on Matts own series).