What is up with the need to specify? The only reason I can think of is that they -- consciously or unconsciously -- want to make sure everyone knows they aren't remotely bisexual. Because otherwise, what? Clearly, we know you're currently interested in women if you're married to one. Or at least I hope for both of your sake that you're interested in her. Not surprisingly, it's mostly straight guys who feel the need to specify this, which also follows with the internalized homophobia thing, since there's more stigma aimed at guys with regards to being gay or bi or bi-curious.
(Yes, I realize some of them may have left it there from while they were single and looking, but that doesn't account for the ones who were already taken when they joined, yet still felt the need to specify.)