What makes you think these issues were only raised after SK informed us of their decision? We certainly let our displeasure at certain of their actions be known. I think you've got the situation in reverse here, honestly. tS had an issue with some things SK did, SK was made aware. SK had a plan (for months now) to drop tS and Mensa in order to veer off and try to form a new sphere, but said nothing until they gave notice of the cancellation of their treaties.
On our side, we actually spoke to our ally when they did things that we didn't like. We didn't just drop them because, hey, maybe our allies are more than just meat shields to us. So SK knew what the issue was, and had a pretty good idea of how to resolve the situation(s). For their part, they actively planned to ditch their allies in favour of trying to gain a better set (the original plan was NPO and Alpha, but I guess that was changed after those two proved untenable in this war), didn't talk to their allies, and then tried to claim that it was some recent decision.
The truth is, SK's been trying to dump its allies in order to build its own sphere for a long time, and the only reason this didn't happen sooner is because they couldn't figure out who to go with, or how to get the ties. This I know, because it was the same damned plan when I was SK gov. Only thing that I can see that's changed is they've shifted from their NPO-Alpha focus to a Rose focus. Same plan, still lied, still being shitty allies.