Bonaire is a 'special municipality' of the Netherlands, and as such, observes the same laws regarding GLBT equality. Same-sex marriage is legal (though rare) on the island.
That said, gay populations are not out or active on the island. There are no gay bars (and few bars of any type). There is no official Pride celebration and there are no gay activist groups. GLBT travelers are unlikely to encounter any discrimination, but they are also unlikely to encounter other gay folks, except by sheer coincidence.