I'm not sure many people noticed the presence of Joan Kennedy at Ted Kennedy's funeral. But I did. Writing about stepmothering skews your vision sometimes, and brings things into focus that interest only you (and, hopefully, other women with stepchildren).

The reason Joan Kennedy would show up to memorialize her ex was clear — she was there to honor a man she was married to for 25 years. But what was less clear, and captured my imagination, was how Victoria Kennedy might have felt about her being there. Happy? Indifferent? Outraged? This is the range of responses women with stepkids I interviewed for my book Stepmonster described when they discussed interfacing and interacting with their husband's exes in scenarios as dire or much more ho-hum and everyday than a funeral.

It is only within the last 40 years or so that women in remarriages with children have begun to grapple with a new variable, the presence of an ex-spouse. Previously, most remarriages with children took place after one parent's death. The presence of a mother and ex-wife in the picture invariably complicates things. As stepfamily researcher Mavis Hetherington has pointed out, stepfamilies, like machines, are subject to the law of moving parts. The more of people there are, the greater the opportunities for interpersonal conflict, differences of opinion, and unreconcilable points of view.

There are exceptions, of course, and much is made of them. With all the media hoopla over the last several years about Bruce and Demi and Ashton (and now Bruce's wife, Emma) being best pals and spending holidays and vacations and evenings out together, highly cooperative, extremely chummy co-parenting involving all partners has a new, high-gloss visibility. And I found in the course my research that this means another great expectation is dogging women with stepkids: you have failed somehow if he and his ex-wife, and YOU and his ex-wife, aren't enthusiastically doing holidays, birthday parties and slumber parties together for the kids. It's what they want and need, after all (it's not, actually, but more of that later).

This expectation percolates even before the marriage happens many times: I have received many emails from women asking me, "Do I have to invite my husband's ex to the wedding?" Most of them have no desire to do so, but feel enormous pressure to go ahead and send out the invitation anyway. The pressure comes from the ex herself, the kids, the in-laws and in some cases even the husband-to-be. It also comes from the culture at large: we seem to have collectively bought into the idea that post-divorce and remarriage reality "should" be easy. Indeed, other women told me that they were expected to go to Christmas or Thanksgiving every year at their husband's ex's place — and even do so without complaint. "I felt like it was modern and hip to do every holiday over there, but I hated it," one woman told me. "I put my foot down but it was surprising how many of my friends thought I was being petulant or unreasonable." Once again I am reminded of pioneering stepfamily researcher Lucille Duberman's insight way back in 1975: "A stepmother must be extraordinary in order to be seen as merely adequate."

The "you should include the ex in everything starting with your wedding, make her and your husband friendly, and be friends with her yourself" expectation is so enormous, and so unrealistic, that it bears careful exploration and dissection before we simply discard it. On this charged topic it might be best to let the facts and the research speak for themselves.

1. High conflict divorces are stressful and unhealthy for children. Exes can address this by shooting for civility rather than BFF status. Mavis Hetherington found that the vast majority of exes are doing something called parallel parenting, in which they more or less stay out of each other's way, and that the vast majority of kids are, to Hetherington's surprise, doing quite well with this arrangement.

2. Hetherington and stepfamily researcher Francesca Adler-Baeder, who is also coordinator of the National Stepfamily Resource Center, found that highly cooperative and highly friendly co-parenting arrangements between exes were actually confusing for children; Adler-Baeder told me in a conversation that such relationship are as detrimental as high conflict ones, leading children to wonder, "If they all get along so well, why did they divorce, and what's the point of being married?" Everyone being civil or even kind is great; love and closeness all around between exes and between a wife and and ex-wife is confusing for kids of all ages, numerous experts tell us.

3. Remarriages or repartnerings with children are remarkably vulnerable and have dramatically higher rates of divorce or dissolution than first marriages. Siphoning attention and energy from the partnership into an attempt to "fix" a relationship with the partner's ex can have disastrous consequences for the couple. So feel free to put your focus on your partnership, not on your partner's ex.

4. For all kinds of reasons, women are more relational and affiliative than men, deriving our self-esteem from successful relationships and often feeling anxious and even depressed when we cannot engineer them. Keep this in mind when it comes to your parnter's ex. You do not have to be best friends with this person for co-parenting to work, and it's not your job to repair what your husband and his ex broke.

5. Keep your eyes open, however, for opportunities to transform civility with his ex into something warmer. Sally told me she was pleasantly surprised when, thirty years after she and her husband divorced and he remarried, she found herself having much in common with her former rival. They now discuss their kids, grandkids, and more. "We're both mothers-in-law now, and there's a lot to dish about," Sally told me recently. My friend Jennifer Newcomb Marine and her ex's wife Carol Marine wrote a book, No One's the Bitch, about their own personal journey from mutual disdain to respect and even affection for one another. It's a good read and a helpful guide, but that does not mean making friendship with his ex your life's work is a good idea for you. If your husband's ex exacerbates her kids' loyalty binds intentionally, for example, or has a personality disorder, your efforts will drain you and perhaps even feed into her sense that you are in the wrong and trying to "make up for it."

6. Feel free to stay out of the fray completely, and to buck the pressure to work a miracle with his ex, with whom your husband may well be in a conflictual or high-conflict relationship. Never going much beyond saying hello on the phone when she calls is fine, too. Lots of women have no relationship with a husband's ex beyond that. Why get involved in the logistics, planning, drop-offs and pick-ups and more if it increases opportunities for conflict and your husband can do it himself? A nice hello at the school concert is fine; you don't have to sit next to each other and go to a diner together after to be a good person, a good wife, or a good stepmother.

Part of succeeding at being a woman with stepchildren is knowing that other people's expectations (many of them ridiculous, such as, "You're failing if you aren't going on vacation with his ex") need not become your own personal burden.