I'm just speculating here, but I think something happened between Tres and Vanessa at or around Dec 17th because that's when Vanessa's twitter activity suddenly became less positive. Before the 17th, her tweets, retweets, and likes were all about Tres and the show. She also appeared to be happy. Now she's retweeting and liking a lot of gloomy quotes about relationships, trust, and fake people. I like them both so it's sad that it looks like they are done.
And the FYI instagram page just posted a really cute behind the scenes photo of Tres and Vanessa. Damn.