Something is wrong here, you need to talk to her about this. Caring for a child is difficult, being a wife is even harder. It is possible she never really wanted you to take the job in the first place but didn't want to seem like a wall to your happiness and success. She could have said yes when infact she meant no.
There is also a possibility that she feels lonely and unhappy when you are not around and this unconsciously continues even after you get back. If her mood is low and she has lost interest in some things she enjoyed doing or complains of tiredness or weakness most times, she may be suffering from depression.