J beat me to the punch, but I think I'll start creating that wedge between happily married straight couples by being the fantasy hot bi for their desires for a threesome. Then I'll be so successful in seducing both the husband and the wife, that they'll fall madly in love with me and hate each other. But that's when the fun really begins.
First I'll start just seeing the wife on the sly. I'll let her know that because of our time together, and because of her involvement into something polyamorous, that she's really more like me than she thought. She doesn't just need to depend on one love, that she's more than that. I'll tell her that her husband really hasn't gotten the "real" woman, that she's been unaware of her polyamory and her bisexuality all this time, but since she's still unsure about where she's at, she'll be needing a lot more practice with me to determine her orientation.
Then while she's thinking I'm only seeing her on the side while screwing both of them in the threesome moments, I'll start seeing him on the sly. I'll remind him that evidence points to her sudden enlivening nature after becoming intimate with a woman, and that her behavior sent my gaydar spinning madly. I'll tell him that I think his wife is actually a lesbian, but ashamed to tell him anything. I'll also try to let him know, if he's ignorant enough, that he was probably the one who made her a lesbian by not being a man enough, and that he is going to need a lot of practice with me to show her that he knows what he is doing to please her in the bedroom if wants to keep his marriage intact and not be taken to the cleaners in divorce court.
And then, watch as the meltdown occurs as both will be wildly manic with their sense of self-worth and base identity in the marriage. And while it's occurring, I'll be getting laid. A lot.
Plan on every single heterosexual marriage being invaded by the bisexuals. We are legion. We are many. And we will own you.