I'm sure that at the time this was released that they felt that they had offered plenty of choice including homosixual bonds.
MODs have made virtually everyone marriageable including one or two that allow for multiple marriages.
Probably the single most gripes that I have seen had to do with Serana and I was one early on. However, since I choose to take my spouse adventuring, I didn't care to use her in that regard, It worked out for the best for me. I ended up marrying Jordis, the House Carl from Solitude.
Keep looking for the perfect mate. As a friend on mine was fond f saying, "There's a rider for every horse..."
I believe that there are plenty of candidates for Steward.