When you married her parent, your stepdaughter might have felt that you usurped her place at home and in her parent’s heart, especially if she was an pre-teen or teen and used to taking care of many family responsibilities, such as preparing meals or housekeeping. When a divorced or widowed parent relies too heavily on the child to take the place of the missing spouse, especially to meet the parent’s emotional needs, it isn’t healthy, according to licensed social worker Susan Pease Gadoua in the Psychology Today article, "When Parents Make Children Their Friend or Spouse." "The child can initiate this type of nonsexual relationship, known as emotional incest or surrogate spouse syndrome, explains Gadoua. When you take over the spousal role, it can create jealousy if she feels pushed out. Encourage your stepdaughter to enjoy being a kid and let her help with some responsibilities. Thank her for doing a great job helping, as you ease her into a more appropriate role in the home.

In addition to taking over responsibilities that she had assumed or been given, your stepdaughter could feel that you are taking her parent’s time away from her. Encourage your stepdaughter and her parent to spend appropriate one-on-one time together while you do something else, such as work on a hobby or spend time with friends, suggests Dr. Laura Markham in her blog, "Aha! Parenting." One-on-one time is also effective if her jealousy stems from the introduction of half- or step-siblings into the family. If the relationship between daughter and parent seems unhealthy, talk to your spouse about it and suggest family counseling to normalize the relationship.

If your stepdaughter doesn’t live with you full-time, she may demonstrate jealousy towards a sibling who does, according to Markham. Spend one-on-one time with the stepdaughter doing shoulder-to-shoulder activities such as working puzzles, reading, crafts and cooking. Assure her that she has an important role in the family, such as being a role model for siblings and being herself. Encourage shoulder-to-shoulder activities between the kids, such as shopping for a gift together or planting a garden with elements she can take home to enhance the family connection long-distance.

Jealousy can create significant in the family and could require professional help. Stepmothers sometimes take on the role of family counselor, according to Wednesday Martin, Ph.D., author of “Stepmonster” in Psychology Today's article, "It's Different for Stepmothers." Avoid falling into that trap, especially when facing concerns such as emotional incest syndrome, evidenced by problems with peers, depression and anxiety, romanticizing or sexualizing of the parent, self-image problems and emotional enmeshing between parent and child, according to emotional incest expert Dr. Patricia Love in the article, "The Emotional Incest Syndrome." Talk to your spouse about your concerns and take them up with a trained specialist who has experience in stepfamily dynamics.