im not 100% on how to sex the stink bugs, but i think the bigger one is female and the smaller one is male?
the smaller one likes to look over the eggs more
so if im correct that would be the male?
Smaller is male, yes. Examples (photos not mine because I’m not this rude):
Green stink bugs. Female on left (you can see her… uh… …) (Source [link])
Dusky stink bugs. Female on left. (Source [link])
Soldier bugs in action (Source [link])
Typically, female arthropods are larger because they have to hold A TON OF EGGS. The parenting behavior you’re seeing is very interesting! Seems like they’re trying to protect the eggs from getting attacked.