Yes, which I think is stupid. Everyone in Skyrim is bisexual? Really?
It's just laziness on Bethesda's part, with no effort to individualize characters.
There should have been an effort for characters to have their own personal tastes in partners, and I'm talking beyond male or female, but even preference for a certain race, or even character build.
Take Aela for example, she seems like the type who would be into a strong, physical fighter. So having high stats in the Warrior line would have her take an interest in you.
Marriage just feels really pointless to me, with no challenge at all in getting a partner, and with no real benefits.