Actually I think his feelings for Mary had been reignited after coming close to losing her, and perhaps understanding a bit more.   In that last scene, they seemed so close, he was ready to confess, both of them allowing the other to go on an adventure instead of complaining about being the one left with the baby, and so on.  I think that if Mary had lived, they would have sorted it out.  But I agree with you, that even if they were still having difficulties, losing Mary like that would be traumatic and heartbreaking.

Yitzock wrote:

Here's what Martin has to say about it.  A lot of it we've gone over before.

https://www.youtube.com/watch?v=7tThtRtMXk8

Nice. Thanks for passing that along; I hadn't seen it before.

I'm struck again how Sherlock actually moves away from John and Mary, a step or two, as he realizes what has happened and the state that John is in. Too angsty for words.