News that Scarlett Johansson and Romain Dauriac had ended their two-year marriage broke on Jan. 25, but a source close to the couple says their union was doomed from the get-go. When Scarlett learned she was pregnant, it was totally unexpected, says the source. That pushed the relationship further and faster than it should have. They rushed to tie the knot soon after daughter Rose’s birth in September 2014. After that, the source says, “the relationship just ran its course. There was no cheating and no big fights.” But signs of trouble were there long before the duo’s split. While Scarlett, 32, who was previously married to Ryan Reynolds for three years, filmed her comedy movie Rock That Body in NYC this past fall, “her living arrangements spoke volumes,” says…