How could this possible have happened?

She probably had surgery done. It happens all the time these days.

Maybe they didn’t have sex until approximately three months after first dating. Not all shemales are obviously feminine.
I kissed a woman once and then found out she was a man. But she sure kissed good. And gave great head, too.

Heshe? Really?

Oh dear, you hear of females turning out to be men, and you would think the usual lack of body hair, Adams apple, width of shoulders, stubble, jawline etc. would be noticeable.

She must have kept herself well covered at all times and had a lack of physical contact with the woman.

Maybe she had some suspicions but in this PC age dare not even bring it up thus assuming he was just a very effininate man, slight if build.

Jazz musician Billy Tipton was married for years, had 2 wives I believe, and no one knew until he died that he had been born female. Yeah, it’s quite possible.

Apparently, this type of thing has been happening for years. You might enjoy perusing through this list of Top 10 Men Who Were Really Women.