Try and stick to information or evidence you have found in original records or sources. Avoid putting speculation into your family files, particularly regarding details of your ancestor's life that are not even remotely suggested in the records. It is difficult for someone over a hundred years later to really understand everything about what motivated their ancestor. A woman being left as a widow in 1855 with small children may have remarried out of necessity to support herself and her children, but whether that marriage was unhappy or not is not suggested merely because it took place early in 1856.
In a similar fashion, your inability to find a marriage record does not mean the couple was not married and the failure to record the birth of a child does not necessarily mean the child was born out of wedlock.
I have wondered if a relative of mine who came home from military service in the early 1900s was somehow impacted mentally by that service. However, I leave that "wonder" out of my records. There's no mention of it in any documents on him, including veteran's hospital records. He seemed to fall away from his family after his mother's death, but I have no proof of actual mental issues at all. It is also possible that he was a little eccentric and didn't get along with his siblings. Or there may be something else entirely.