I want them to switch from time to time because

Then you must read Thirst

Huh, I didnt even realize pretty all much of rare switch couples were from managa. But yeah absolutely seconded on Thirst!!!!!

https://www.mangago.zone/read-manga/playtime_with_hakdo/
https://www.mangago.zone/read-manga/like_a_tidal_wave_from_pheromone_shower/
https://www.mangago.zone/read-manga/zero_at_the_bone/
https://www.mangago.zone/read-manga/rise_of_moonsoo/

My favorite is Dark Heaven! It’s so good

Then i recommend Playtime with Hakdo. It's manhwa and they switch (=・ω・=)