Hello, whenever I do a "One on one" with a slime girl and let her "Take the lead" in the sex act, the game crashes to desktop. I'm using version 1.0d

It probably has nothing to do with slime, rather she likely rejected you as a potential partner leaving her no options to choose from. There is already a fix for that: https://itch.io/t/1167355/bugfix-for-10d-v4a