So, canonically, Daniel and Amanda have sex after Daniel has spent considerable time around Johnny, but now that Daniel will be around Johnny all the time, Daniel wants sex all the time, and it's more than Amanda can handle, so she encourages him to take a lover. Because Cobra Kai is built on insane coincidences, Daniel picks a guy who is Johnny's ex-boyfriend, but Johnny's still in the closet and never got over his ex, but was never able to come out.

Angst with a happy ending preferable.