But, Severus did what I learned to do: say the truth aloud for reinforcement. Remus is courting him and laughing at him wouldn't do his case any good.
I think, like all insecure people learning to navigate through life, Severus might fall back into what he was used to, but he realizes that there's more good now than before.
As to Severus' teasing, I think that's the unrequited sexual frustration growling. *lol*