Her letters alternate from sunny highs to dark, cloudy lows.

Definitely what I thought.
She reminds me a bit of my grandfather, who would hike and run on the shore for miles every day even in his 70s, until his sight has rapidly been going since he turned 82 or so, and he is very down about it. No upside though.

But yeah, she goes from one thought to the next, from high to low, and from low to high. As if she's using the high energy to propel her into the darkness, and then needs the high to recover again.

I think that Cowboy Poet thing sounds marvelous, would've loved to sit in on one as well.

As for your sister becoming more of a recluse, it seems as people grow older, they turn more reclusive. Then again, I've always been reclusive, so who am I to talk?
The internet, a place for recluses to be gregarious, so maybe Lois would've liked it. Who knows.

Thanks for sharing, Carol.