Walter claims he knew that Kitty had no feelings for him when they married, why did he still want to marry her?

Even though Walter knew that Kitty did not have much in common with him and did not love him, he still wanted to marry her because he simply loved her. He had no illusions about her silly and frivolous nature and that she had been brought up to be ignorant and vulgar, he loved her despite her inadequacies and only wanted to be near her.