Think about it, if you're dating a lesbian, she has no desire to cheat on you with men, since she has no sexual attraction to them. If she ever ended up cheating on you, it would be with a girl, so you aren't really cucked to the same extent as you would be with a straight girl cheating on you with a guy. In fact, she might actually bring the other dyke along for a threesome. It's kind of like being muslim and finding out that your two wives are having sex, but instead of having them beheaded or some shit, you just fuck both of them.