I remember two of them:
https://www.mangago.me/read-manga/life_ain_t_so_bad/
Pornstar x fan
https://www.mangago.me/read-manga/mike_chan_to_kuro_sense/
Student x teacher
Both of them hint at switching, but never go through with it.
(Edit) Remembered two more:
https://www.mangago.me/read-manga/hi_manyuaru_ren_ai/
It’s a oneshot, some elements o...... reply
