DougR says:

ever seen a picture of Lincoln's wife? That could explain his "shyness."

A couple of rather ugly pictures have been widely circulated, and are likely to be what most people remember, but a more recent Google image search will get some rather more favorable ones. Mary Todd was considered quite an attractive woman in her time, although perhaps less for her physical attributes than for her ability to "throw a great party."

Since she was from the Confederate state of Kentucky, she was openly accused during the war of being a "spy for the Confederacy" by many northerners, and of being a "traitor" by many of her (former?) friends and family in the Confederate states, which must have been something of an unpleasantness.

One of her three sons died while Lincoln was in office, and another
shortly after Abe was murdered. Some say that the son who died while Abe was president was her "favorite," and that her mood was significantly affected; but the reports of actual effects are rather vague.

One story is that Mary Todd was seriously worried about her poverty after Abe was gone, and there are some tales about some rather bizarre things she did because of that concern. There was no "retirement benefit" for ex-first ladies at the time. A son had her judged "insane" and she spent a month or so in a care facility (various less pleasant names were used for the facility at the time) but a "political friend" was able to get a retrial and she was found "sane(?)" by the second jury.

Stories about her strange behaviour relate mostly to the period after Abe's murder; but of course different authors give different accounts. There are a reasonable number of incidents in the latter part of Abe's presidency that do show at least the "public display" of a strong and apparently conventional marital relationship.

John