Sometimes they'll even switch up those professional relationships eg. Aljaz and Joanne. 17 pros this season whose not getting a consistent pro partner?

And in the last few years what have the pairs been?

Last year I think it was:
Anton & Natalie
Kevin & Karen
Brendan & Joanne
Pasha & Ola
Giovanni & Oti
Aljaz & Janette
Trent & Aliona
Gleb & Kristina

last year, if I remember correctly, there are no actual partnerships

there were a few solo pro dances, obviously karen and kevin - can't remember anyone else! did Jo and Gio do one?

for the group pro dances I don't mind who dances with who tbh I quite like that they mix it up and don't have "set" partners

This ones a bit over my head, but thanks Tom.

The trend appears to be not to have fixed pro partnerships, though some do dance together more often than not, particularly those who are real life couples.

And of course, as it always does, it will depend on which pros get knocked out of the competition early, and then also on the genre -for example, Aljaz will usually do a ballroom solo couple routine at some point, but obviously not with Janette (last year I think he danced with Jo and Oti in different ballroom routines).

It is always sad when someone gets knocked out

Yes I think they mix it up a bit now.

Jo and Gio did a gorgeous routine during Seal's performance on the show.

They certainly did.