I’m not understanding why seme have to take Pheromones Stimulants?

I bet his mom made him

Sorry ahead of time for the long post.

My guess (do not take this as gospel as I can't read the language the raws are in), is that they put him on them in an attempt to get the "differentiation" between him and his "partner" to a higher level, so that when they eventually marry they would be more likely to produce an alpha heir. The mother had said in an earlier chapter that Taixen (sp?) and Luo Cheng have a high differentiation compatibility, and are more likely to bare an alpha child between the two of them. So apparently in this world differentiation compatibility between two people has a high affect on the secondary sex of a child. And since Taixen was (is) supposed to marry they bluish haired dude, the mother probably wanted to raise that compatibility between the two because she is more interested in keeping control of all the families and businesses in her family line and not letting them go to other heirs.

Same

Awwww Now I understand Thanks (づ￣ ³￣)づ