All these men who have cheating wives. Yes, you may be able to convert her to cuckoldry (where she fucks other men, with your knowledge), but you have to remember, cheating is about her in control. Some like cheating because it gives her more options, and no meddling from you. When it cums to getting fucked, she wants you out of the picture.
She may even enjoy hurting you, without the reprisals. Because you don't or won't know.
There is of course many risks for her, including STD's, and psychotic, abusive, or opportunistic lovers. But these are not much different than when a man is cheating on his wife.