Should I keep my mouth shut?

Hi guys, well I really need an advice about something. My best friend ex boyfriend is in love with my cousin the problem is my cousin have a crush on him too buuuut both of them are closets bi? I wouldn’t say gay because they likes girls at least the ex boyfriend concerning my cousin I think he’s dating girls in order to hide his true self, I’m so sad for him but this is not the question. They both know I looove yaoi and I’m always supportative for all gay couple in our circle of acquaintances. It’s been already 2 years since my cousin told me about his crush and just few weeks after that my bf ex boyfriend who’s also my friend told me he is in love with my cousin seeking for advice , the two of them makes me promise to never tell. I’m kind of pissed now because I think they’re engaging in short pointless relashionship and always come to me to ask what the other’s doing. Do you think I have the right to say something? Or at least set something to make them moves? Did you ever face this kind of situation?(〜￣△￣)〜