How do we know that Taja and Siro WEREN'T sleeping together?
I mean,we don't get to see EVERYTHING these characters do!!!
Besides,after what happened in Flawed Victory the idea was put in their heads.And when an idea like that gets put in your head(especially when it's about somebody you live with and see on a regular basis),it doesn't just go away.
And I'm sure there was a mutual attraction.
I should have known those alien maggots booby trapped this sub.