Henry and Paige first met when Paige's charge (as she became a full-time whitelighter) was one of Henry's paroles. They often bumped in to eachother as they were both trying to save the same young man. Henry assumed she worked for the goverment as she seemed to know various things and managed to track down the missing father of a baby put under Henry's watch. (This was down to her scyring)
They soon got together as Paige healed his gunshot wound. This was the first time Paige healed and healing can only be activated by true love. Paige soon revealed her witch inheritance and Henry accepted it, leading to him proposing. Paige accepted.
Later, when Paige was preparing to battle the demonic clan, The Triad, she believed there was a strong chance she might die, therefore Henry protested if she got back alive, they would wed straight away. Of course Paige come back alive and well, and soon became a wife herself to Henry.
Henry is the father to Paige's twins.