Theory: Barney and Lily had sex in Season 2, but Ted doesn't know it

Yesterday I read that it’s been a while since any new theories about the show have been posted, so I wanted to share one I have (apologies if it’s already been posted).

Barney and Lily had sex in Season 2, when they were living together, which I deduce from:

- Things were going pretty well until “that night” when “they watched TV and went to sleep without anything happening,” at which point Barney panicked and kicked her out of the house. Isn’t it more plausible that Barney panicked because he slept with his friend’s ex, rather than because he didn’t make a move (if that were the case, he wouldn’t have any friends)?

- When Lily disagrees with her friends, she argues until she’s blue in the face and usually gets her way—which doesn’t happen here. Could it be that Lily agrees it can’t happen again?

- We know the story from Ted’s perspective, but it’s reasonable to assume he was never told about this (Lily is capable of keeping big secrets, when they’re her own, like the credit card debt). Barney and Lily knew this would break up the group.

- The show often hints at the mutual attraction between Barney and Lily, and at that point she was single, while he—as we later see with Robin—has trouble controlling himself in those situations

I’m curious to hear if this theory seems credible to you or if there are facts that discredit it.

* Again, I’m sorry if this has been posted before