Recently in a Pathfinder campaign I encountered the following in a combat situation, after our group made an ambush on a castle inhabited by a small Gnoll clan. Our group clearly had the upper hand and the Gnolls started to evacuate the castle. On my turn my Thief went behind a house to get stealth again, but when he run around a corner he just ended up in melee range to a Gnoll who was covering a flank while behind him the Gnoll-children were being evacuated by 2~3 other Gnolls. So I said to our GM that I am gonna make a melee attack against that Gnoll. Which our DM responded to with:
GM: So you intend to kill the children?
GM: So why you want to kill that guard then?
ME: Cause he is threatening me and I am in melee range with him.
GM: He is threatening you because he is there to protect the children. If you just lower your weapon and walk away he wont even attack you.
ME: But how my character is supposed to know that? He is currently in melee having a weapon pointed on him, by someone belonging to a clan we just wiped out halfway over the last few minutes. Why would my character take the risk turning his back to that guy?
GM: Cause that's common sense that while guarding the evacuation of the children, he had no reason to start fighting you, if you not attack him.
ME: Ok, so since I clearly lack that common sense you talk about, tell me please, what would my character then do instead now?....
So I ended my turn after using my action for moving back to where I just started. This felt very unrewarding and despite I still disagree, that no matter what alignment my character has, he wouldn't have just turned his back to someone pointing his weapon at him, after my character just killed half of that enemies family. No matter what was going on behind that enemies back. But for the sake of this question lets focus on the following:
If I end up again in a situation, where everyone at the table agrees, that the actions I want my character to do are contradicting with what my char would be doing by common sense, how can I solve the situation without giving up player agency, despite I as the player lacking the interpersonal knowledge of what my Character is expected to do by 'common sense'?