I agree that if we have to interpret the scene one way vs the other, the scene read to me as if Ted was broken up because The Mother (Cristin Milioti) was dying or that they knew she was going to die a lot sooner than they'd expected, and that this is why they were back at Farhampton (where Roger Bart recognizes them, referring to them both as "The Mosbys,") to get as much time together as possible.
It's interesting that there was no narration from Bob Saget Ted at all in this episode, so we can't really explain away with the whole "Ted's an unreliable narrator" excuse. In fact, now that I think about it, has Bob Saget narrated any
of the flash forwards where we see Ted and The Mother as a couple? If not, it would seem to imply that what we're seeing is in fact the "raw, unedited" truth of the scenes not affected by Ted's narrating (i.e. events as they actually have happened.)
Even when the show did the whole "How Your Mother Met Me" episode, it wasn't The Mother narrating (the way Robin narrated in "Symphony of Illumination") but it was Ted. This, plus Ted's wish that he'd met the mother 45 days earlier than he did when he went to see Summer a few years ago seems to lend credence to the idea that Bob Saget Ted is telling his kids the story of how he met their mother because their mother has died/been dead for a while in the year 2030.
Dramatically, it would make perfect sense. A character like Ted, who spends 9 years searching for his true love, finds her, has his time with her, and then loses her tragically, would of course revel in being able to tell the tale to his kids. The Mother's line ("I don't want you to be the guy who lives in his stories. Life only moves forward.") would seem to support this, and we've seen from the brief snippets we've been given of their life together that she "gets" Ted more than any other woman he's been with.
Random other theory: (And, I think someone may have mentioned it already in this thread) - Is it possible Future Ted is telling his kids the story in 2030 via DVD? Is it possible he knew he
was dying, and because he loved his wife and family, and his penchant for storytelling, he recorded as much of the story as he could before he finally died, (in 2024) and then, six years later, it's the Mother who plays the DVD for her kids so that they can understand how much Ted loved them all? It would certainly give added meaning to The Mother's aforementioned lines about living in his stories - perhaps that's even the catalyst for him to sit down and record the DVD? We've never actually seen Old Ted (as voiced by Bob Saget)
Total, random sidebar:
--Can't wait to see Robin's mom in action.
--Props to the writers for bringing back "Swarley."
--"Sue Tup." Brilliant!