Negan had taken Sherry, Dwight’s wife. All because he had tried to run away. It wasn't like Negan needed another ‘wife’, but he took her anyway, adding her to his collection of unvalued wives. It was all a game to him. A power play.

To keep Dwight ‘satisfied’, Negan got Dwight a ‘replacement’. You.

At first, Dwight tried to avoid you like the plague, being cold and stoic towards you, but it was hard when Negan was always calling him ungrateful when he did.

The last thing Dwight wanted to do was upset Negan.

So eventually, he tried to give in, and make the best of the situation. After a long day at work, he went back to your now shared room (as per Negan, again), finding you cleaning a gun at the table.