The tags and description seem to be at odds with each other. How can there be a cheating tag if the MC''s whole goal in life is sharing his wife with any and everyone? If she sleeps around without him knowing he literally wouldn't care one bit. If she leaves him completely then it's game over.. so cheating tag seems to not be appropriate here.
It's entirely possible for him to want to share his wife but for her to go outside of what he's looking for. For instance, he wants to watch a man fucking his wife, so they have an arrangement for that, but she ends up liking it a bit more, or maybe even falling in love, and goes behind her husband's back, i.e., cheating. If he finds out, he might be okay with it because he had fantasies along those lines, or he might not like it, because that's not what he wanted. Either way though, it would still be cheating.
As far as the tags go though, I always thought that it was from the perspective of the MC, so "cheating" would be the MC cheating on his/her partner (with "netorare" being the tag used for the partner cheating on the MC).