Stress can have both positive effects, when it helps to motivate your wife to do her best, and negative effects, such as causing anxiety when she feels overwhelmed. Chronic stress is dangerous, as it interferes with her ability to concentrate, causes wear and tear on her body and results in chronic fatigue, according to the American Psychological Association. Watching your wife continually stressed out is difficult; and while she needs to take responsibility for her feelings and actions, there are steps you can take to create a peaceful atmosphere for her.

Notice when your wife seems unusually moody or withdrawn. She may become teary or agitated over something you don't consider an issue. The little things that never bothered her before may cause her to snap at you or lead to what you perceive to be unnecessary arguments.

Avoid ignoring changes in behavior. If your wife suddenly begins to drink a second glass of wine each evening or seems to be indulging in junk food on a regular basis, consider the possibility that she may be self-medicating, suggests Judy Ford, licensed clinical social worker and author of "Every Day Love: The Delicate Art of Caring For Each Other."

Resist the urge to solve your wife's problems. Rather, be compassionate and empathize by asking if there is anything bothering her. Put your arm around her and listen to what she has to say. Offer your advice if she asks for it.

Check your own stress levels, suggests Ford. Stress is often shared between partners. If you are stressed about a project at work and you come home in a tense manner, your wife is likely to pick up on it. The tension may make its appearance in your communication and interactions with one another.

Ask your wife what you can do to relieve some of her stress and then follow through on her suggestions. This could mean taking on additional child care responsibilities or increasing your share of household chores. Perhaps she needs a set amount of time to herself each day. Do what you can to accommodate her wishes.

Strongly suggest that your wife seek professional help if her stress levels do not diminish with life changes such as receiving additional help around the house, beginning an exercise regimen, talking it out and getting more sleep. There may be an underlying issue, such as anxiety or depression, according to Womenshealth.gov.