My fiancee and I have decided to be 100% upfront with all our vendors as immediately as possible with the fact that we're a same-sex couple, so that they can refuse service if they want to and we can find a different vendor. What actually is the best way, in an email or in person, to ask a vendor whether they provide services to same-sex couples without sounding like we're going to make their lives miserable if they don't, and making it clear that we respect differing values-- we're asking because we need to know, not because we're going to go ape-you-know-what if they turn us down.