God love her, the disappointment at not being able to dance and having to watch on from the side lines must be crushing.
I think it's always going to be awkward if/when the sleb does better, and it's happened before on Strictly, but it's easier for a thrupple when the injured pro at least did the choreo (e.g. DWTS Shana Burgess/James Hinchcliffe/Jenna Johnson). Last night's was Couples' Choice so outside choreographers (was it Tommy and Lizzy? Looked like one of theirs).
Add to that Amy's anxiety over losing her place permanently when she was so ill and it's bound to be a body blow. I hope she'll rest rather than force herself back too quickly just because they did well and she fears being benched in the future. I liked the routine but it wasn't 10s for me.
All couples choices should be done in the same week imo.
As others have said, they are usually overmarked and the narratives behind the contempowafts often make it very hard to judge objectively.
As for the benching itself of uninjured pros, I hate it. I'd rather they had a set troupe and you were taken on as a troupe member/a permanent pro for all Xmas/charity specials and got "promoted" to the main cast when there was a natural gap/a pro moved on by choice. Not being announced as a new Strictly pro but then seeing new signings or being picked up/dropped/benched randomly. #justiceforChloe/Cameron
Or if you have surplus pros every time then they ought to draw lots on the benching. I'm really not sure I believe pairing is down to the chemistry tests/heights and they can't share out the sitting out. Or you win the 
and leave! 
Joanne, Aliona, Camilla you were pioneers!! 
Edited