My bf 22M and mutual friend 22F smoking weed alone. Am i overthinking?

so me and my boyfriend are dating for 2 years… Currently he is in our college town and im at home town due to some work. So we have a common friend - A

She asked my boyfriend to smoke weed together initially she said she would ask her situationship (boy) to come over so three of them can smoke joint together. But later the girls situationship bailed out at last moment. The joint was already lit while waiting for the other boy and since he bailed at last minute they smoked that joint later she went to her room and my boyfriend at his . The whole session was of 30-45 mins

He told me about this today after 2 days as i was on trip and we couldn’t talk . So we have clear boundaries that this is acceptable or it. It isnt for both of us But he said he thought that boy would also join so he said yes otherwise he wouldn’t. He is extremely sorry and is saying he didn’t felt it was right. I trust him he did nothing like this in past.

Still im feeling conflicted

Ps - Also i know the girl we have been friends from start of our college there isnt any sexual tension between them that im sure of

Td;Lr - My boyfriend and friend smoked weed together as her situationship bailed out at last moment