the demon leader’s lover
this? although, the white haired guy you're speaking of is the 2nd ml.
https://www.mangago.me/read-manga/yang_energy/
this seems similar but i only skimmed a bit (white haired ml, yang energy mc, crossdressing(?))
https://www.mangago.me/read-manga/the_demon_leader_s_lover/
yes, it’s this one! thank you so much!!!
haven’t read this one but it looks good, i’ll add that to my list!
the mc has a lot of yang energy and he was sent to the emperor/crown prince (ml) who has long white hair and blue eyes. The mc’s family is evil and is using him as a spy against the ml even though they kicked him out. Idk if this is relevant, but he also dressed as a woman while in the palace. Tbh i forgot a lot of the plot cos i read it so long ago, but any help is appreciated!