RUourcouple, by "we," do you mean each of you has had separate no-shows, or are you trying to date as a couple? People interested in dating a couple, especially bi-women (not sure if a HBB is your hope, but it's the most common one for couples), are few and far between to begin with. Since they're also the most sough-after demographic, they also have a huge selection of possibilities, meaning attracting their interest can be very difficult. And, often (not always, of course) those people considering dating a couple are new to poly, since most of the bi poly (men and women, but especially women) I've encountered stop dating couples fairly quickly. Meaning, it's also not surprising they get cold feet when faced with the overwhelming proposition of being confronted with a unified couple.
I am not saying people dating singly always have luck, just like mono people on mono-oriented sites don't, but if you're only dating as couple you're likely to have markedly worse luck.