this is quite common in the manosphere realm and among mature and middle aged couples eg cuckolding, dogging, swinging, partner sharing etc Most women have an inquisitive nature and have most likely fantasised or thought about it but will rarely initiate it - it is up to the guy to bring the subject up, organise, arrange it and make it happen and the woman will generally go along with it.
I think most women would entertain the idea but the social conditioning prevents it as they don’t want be seen as slutty, dirty and horny. Ultimately woman are more sexual than men.

Anyway a great topic and discussion!