Honestly I didn't know from the beginning
My brain is telling me that in the first few chapters Neil told Jensen or at least Jensen has an idea (or was I hallucinating...)
Okay. I just back read and it was on chapter 3. Niel used "husband" instead of "wife" and Jensen noticed that bit and had a feeling that something was odd about Niel and his statement, but he didn't assume so this is why he was confused when the neighbor presumed that Jensen is Niel's bf.
Oh I see
Does Jensen know that Niel swings that way? I thought he knew from the beginning.