yes, I've known some people who are aware of their partner's infidelity but choose to to stay or have a "don't ask, don't tell dynamic". To each their own, life is about choices and everyone needs to make their own.
I've noticed there's a common double-standard when it comes to "being open about it" as you pointed out. Mainly that one person wants to have the freedom to be with others while keeping their primary partner, but they don't want their partner to have the same freedoms. Which then leads to cheating.
However, there's no rule saying you need to life the same life. There are a gazillion paths you can take and the best part is you get to decide which route to take along your personal journey.
I encourage you to (safely) follow your curiosities. Who knows, maybe you'll stumble upon something life changing :-)
Thank you for reading, and for your kindness. I appreciate you.