Sex with other couples

hello ladies I would like some opinion about this topic. My husband and I have been together for almost 4 years. he was always the guys who in previous relationships have treesome and share his partner with others for fun . Everything sexual of course no feelings involve because hes very open. Then he married me and I was not into that and he understood but now the conversation came out if i would be okay doing this since we being together for this long and sex became a routine and less during years.

he thinks this would help to get more intimate and have fun.

I know the idea is crazy but makes me think if this could out control or it will really help? ( I dont my give a try) but at the same time I dont want to regret it later.

please let me know your thoughts! thanks