Blending a family isn’t for the faint of heart. Between the parenting styles, shifting roles, and emotional landmines, it can feel like you're building a house during an earthquake. But one of the biggest pressure points—one that can destabilize even the strongest partnerships—is the ongoing presence of an ex.

Whether it’s your ex, your partner’s ex, or both, navigating those relationships is tricky. There’s history, hurt, differing expectations, and sometimes... a complete lack of boundaries.

But here’s the truth: your peace is worth protecting.

And in a blended family, peace doesn’t happen by accident. It’s built—intentionally—through clear, respectful boundaries that honor your relationship while creating space for healthy co-parenting. As a licensed marriage and family therapist, former stepmom, and expert in blended family dynamics, I’ve seen how transformative these five boundaries can be.

1. Boundaries Around Communication

There’s a fine line between being cooperative and being overly involved. It’s not uncommon for exes to text late at night, vent about their personal lives, or expect immediate responses to non-urgent matters. This kind of access can erode the intimacy and stability of your current relationship.

Set This Boundary:

All communication between exes should be respectful, child-focused, and during reasonable hours. If it’s not about the kids, it doesn’t need a reply.

You and your partner should be on the same page about what kinds of communication are appropriate and how you’ll handle situations when those boundaries are crossed. Some couples find it helpful to use co-parenting apps like OurFamilyWizard or TalkingParents to keep communication structured and documented.

2. Boundaries Around Decision-Making

One of the biggest sources of conflict in blended families is power imbalance—especially when an ex tries to influence parenting decisions in your home.

While legal custody agreements define major decisions, the day-to-day parenting inside your household is yours and your partner’s domain. If an ex is constantly questioning your rules or undermining your routines, it’s time to reclaim your authority.

Set This Boundary:

What happens in our home is our decision. We respect your parenting in your home, and we expect the same in return.

This doesn’t mean cutting off communication or refusing to cooperate—it means drawing a firm line that supports healthy boundaries and mutual respect across households.

3. Boundaries Around Access and Presence

Pop-ins, uninvited drop-offs, or lingering during transitions can create awkwardness and emotional confusion—for the adults and the kids.

If your partner’s ex (or yours) is frequently showing up without notice or involving themselves in your personal space, it’s essential to set physical and emotional boundaries.

Set This Boundary:

All pickups, drop-offs, and visits should happen at agreed-upon times and locations. Our home is our private space.

If necessary, consider neutral ground for exchanges. It’s okay to prioritize your comfort and emotional safety—especially when you're trying to build a calm, secure environment for your children.

4. Boundaries Around Loyalty Traps

Children in blended families often feel caught in the middle—especially if one or both biological parents aren’t respectful of the new relationship dynamic. Comments like, “She’s not your real mom,” or subtle criticisms of the stepparent can foster insecurity and emotional distress for kids.

It’s not just painful—it’s harmful.

Set This Boundary:

We will not speak negatively about each other across households, and we ask that you do the same. The kids deserve to love everyone in their life without guilt.

If the other parent isn’t open to this boundary, you can still model it consistently in your home. Kids notice emotional safety, even when the adults don’t cooperate.

5. Boundaries Around Your Couple Bubble

In a blended family, the romantic relationship can easily get lost in the shuffle. Between ex drama, co-parenting logistics, and kid needs, your connection can start to erode. That’s why the most crucial boundary might be the one you protect between the two of you.

Set This Boundary:

Our relationship is a priority. We will protect time to connect, communicate, and recalibrate—without letting ex-related stressors steal our focus.

Create rituals that nurture your bond, like weekly check-ins or screen-free evenings together. Talk openly about how outside stress impacts you, and support each other through it. When your relationship is strong, your whole family benefits.

A Final Word: Boundaries Aren’t Walls—They’re Bridges

Setting boundaries isn’t about being rigid, cold, or confrontational. It’s about creating emotional safety—for you, your partner, and your children.

As a former stepmom, I know the emotional complexity this journey demands. I also know that attachment science shows us something hopeful: children (and adults) thrive when relationships are consistent, emotionally safe, and secure. Boundaries help create that environment.

If you and your partner are navigating the ex-factor and feeling overwhelmed by the pressure, you're not alone. The challenges are real—but so are the solutions.

And if you’re ready to move from chaos to clarity, check out my course: The Blended Family Alignment Blueprint. It’s a therapist-backed roadmap to help you and your partner end power struggles, align your roles, and build a rhythm that finally feels like home.

Because peace is possible—and it starts with you.