Hound of the Baskerville

[Asila]

He was married to Mary until after she died (in the interim where Holmes was also dead OH MY GOD I'M A FUCKING NERD) but it mentions him being married at least once after that, leaving dedicated readers with little time on their hand to conclude that he'd married again. I'm *pretty sure* there's argument for him being married twice after Mary's death, but I'm too lazy to look it up.
That and Watson mentions several times during The Solitary Cyclist (seriously people, it's getting out of control here) that he was hoping that Holmes' concern for their female client was so great because he was considering her as a romantic prospect.