Here's the thing about Dil
And the take-away message from this movie for me. Even with the goods Dil is packing under her skirt, she's still more feminine, more appealing, more charming than a lot of women who are conventionally equipped. Any old harridan fishwife can produce offspring and a provide a tidy receptacle for their partner, but the emotional and intellectual presence of Dil is what really draws Fergus in and keeps him interested. It's a credit to Fergus and his integrity as a thinking, feeling person that in the end, it's these aspects that he values, rather than being forever overwhelmed and repulsed at seeing what he saw, and knowing what he knows. He cares more about the content of your character than a few quirks of physiology.
Although all that being said, let's not be too naive. Fergus clearly has an interest in men outright, feminine men and manly men, from the rapport he establishes with Jody early on in the movie. The way the camera moves during a certain sequence suggests a romantic interest in and fascination with Jody.