If I found my wife in bed with another woman, I would still consider it cheating and act of consequence - and the woman will better get out fast, because I would apply gender equality and treat her like I'd do to a guy. Some guys say that "with another woman it doesn't count", but for me it's bullcrap. There's still the lying, the deceiving and hiding.
I'm not the jealous type and we are always open for honest conversation about exploring, but any form of bad faith and deceiving closes the deal for me.