Technically speaking, while female players have three attractive male romance options to choose from (Astarion, Gale and Wyll), the straight men do have Shadowheart, Lae'zel and Minthara, so the playing field is actually pretty even!
As a male I would have to differ in opinion here.... The three female options are just not that attractive at all. Laezel is like a 2.5 , Shadowhart a solid 5, and Minthara a 6 -6.5 at best for physical beauty. And all three have personality's of 3 and lower on a scale of 1-10. They are just not that appealing to either hang out with (personality) or enticing to look at (physical attractiveness). And Minthara has the worst personality of the three, unless you as the "partner" are fond of being patronized, victimized, and are in general a masochist in relationships. In that she delivers in spades.
So I agree with the OP on several points and yeah, I am American and most Americans tend to be prudes regarding sex, but that is because historically the first groups to migrate from Europe to here were puritans, and that has affected how the "American culture" has developed over time (sadly). So yes, I agree this game needs more romance options that are appealing to a broader spectrum of players that what is currently offered. The current female character options are all just bad choices to have any kind of game relationship with.