In the short story "A Temporary Matter" by Jhumpa Lahiri, Shukumar is portrayed as a character who is struggling with feelings of guilt and regret. He feels that he has let his wife down and that he is responsible for the breakdown of their relationship.
One piece of evidence that supports this is when Shukumar thinks to himself, "He deserved the indifference she had shown him lately, deserved her attention to be focused elsewhere." This suggests that Shukumar feels that he has done something to cause his wife to lose interest in him and that he deserves to be ignored.
Another piece of evidence that supports this is when the narrator describes Shukumar's reaction to finding out that his wife had been pregnant and had lost the baby while he was away at an academic conference. The narrator states that "he was overwhelmed with a sense of failure, as though it had been his responsibility all along to keep the baby safe." This suggests that Shukumar feels guilty about not being there for his wife when she needed him and that he blames himself for the loss of the baby.
Overall, Shukumar's feelings of guilt and regret about the state of his marriage suggest that he has a low self-esteem and does not value himself very highly.