New "security updated" versions of Unity use different entry point which causes BepInEx to crash. BepInEx is aware of that, but there still has been no fix yet
Unlucky, you may only wait until either dev drops the update or bepinex fixes their loader (or crack the game any other possible way)
The easiest way to still "crack" it tho would be to ask someone who has bought access their Registry files from
HKEY_CURRENT_USER\SOFTWARE\UnzippedGames\SextingmyGF, there are some settings and data along with four CacheEncryption* keys, and SSCacheEncryption* which presumably used to save game version in an encrypted format to check if you logged in before or not