Kate should have some Corruption by this point in the game (unless you deliberately avoided Corrupting her). A 0 Corruption Kate doesn't give the MC a Handjob during the Serving Game nor let him fuck her in the Barn.
You can do Kate in the barn at 0 corruption, just with no Rick involvement, anal when cleaning is also available even if Thomas and Claire are already in the lower floor, which i find funny (There is no dialogue variation, but Thomas standing behind the counter and saying nothing about it makes me laugh).
About the avoiding corruption, i like playing differently to see different dialogues, for example, MC isn't a virgin/doesn't mentions it/lies about it (Doesn't matter if you try to make Tia, Kate, Penny, Frisha, Arianna or Mira MC's first, there is no dialogue regarding it in most cases and in Mira's case the MC mentions being regretful for not waiting to have his first time with her), first anal time of MC should be Kate, otherwise MC gets +1 corruption (There is no dialogue changing with anyone else, but Kate, if it isn't MC actual first time he lies, which rises his corruption, if it is his first time, there is no lie, which increases Kate affection), haven't touched corruption other than with Tia and Raaisha (Mostly to unlock Umah content), and there is plenty in the way of dialogue variations as corruption increases.