You know you've been married a long time and aren't listening to your spouse as much as you used to when:
1) You read through a brochure for a conference that looks interesting and look through the talks and the speakers. One of the names seems familiar and it takes you a few minutes to realize, "oh DUH! That's my husband!". Yep, Mr. Gaia is going to be speaking at a conference and I'm sure he told me, but I didn't hear it.
2) His schedule goes in one ear and out the other - "you're speaking to who, when?". "Okay, you have a meeting Monday night - where is that and for what?"
3) Your wife explains the great confluence of events that will lead to her actually getting to see a dear friend and you have no memory of any part of the conversation.
4) Your wife tells you she really likes one of the new shows you're taping and you watch it and erase it while she's at work.
Mr. Gaia and I have hit that stage. Sigh.
Of course, on the other hand, we understand each other's rhythms better than ever.