In Chapter 5, there is more to show that Curley’s wife doesn’t love him than that he doesn’t love her. She says:
‘I can’t talk to nobody but Curley. Else he gets mad.’
It’s clear that Curley’s wife didn’t marry him for love:
‘Well, I wasn’t gonna stay no place where I couldn’t get nowhere or make something of myself, an’ where they stole your letters. I ast her if she stole it, too, an’ she says no. So I married Curley. Met him out to the Riverside Dance Palace that same night.’
She goes on:
‘I don’ like Curley. He ain’t a nice fella.’
As for Curley’s feelings about his wife, the first quote reminds us that he’s jealous (see the first quote), but that doesn’t necessarily mean that he doesn’t love her. The most we can conclude from that is that he isn’t sensitive to the fact that she is lonely.
Curley’s reaction to her death tells us a bit more. It is Slim, not Curley, who gently checks her neck and touches her cheek. Curley never expresses any sense of loss or sorrow about losing her. Instead, he is furious and determined to get Lennie. Later, when Slim suggests that Curley should stay with his wife, Curley insists that he’s going to be the one to get Lennie.
Slim adds to this impression in talking with George, who wants to protect Lennie by bringing him in rather than shooting him.
‘If we could keep Curley in, we might. But Curley’s gonna want to shoot ‘im. Curley's still mad about his hand.’ (emphasis added)