Why did Arjuna share his wife with his brothers? When his mother clearly didn't mean to tell him that? Why didn't Draupadi have a choice?

I don't want to offend anyone but I think this was pretty stupid. Mata Kunti definitely didn't mean for him to share his wife obviously you should understand when a person didn't intent on saying this. I don't know what was our book trying to teach us here, and why the hell is there not a choice of Draupadi. "Ma ka baat ko hamesha follow karo", i sincerely disagree, Arjuna is a grown adult and should definitely have used his brain there instead of this old fashioned out dated ideas. "Everything was part of the plan of Krishna" that just adds more variables and doesn't really help with my question, why couldn't he pick out another plan? Why was this necessary? I'm seriously in need of answers why didn't she have a choice