The Silent Killer of Long-Term Relationships: Untreated Mental Illness

When we think about why relationships end, most people immediately point to incompatibility, infidelity, or “falling out of love.” But after over a decade of sitting with couples in the therapy room, I can tell you one of the silent killers of long-term relationships and marriages is often overlooked: untreated mental illness.

When Love Isn’t Enough

Many couples come to me heartbroken and confused. They’ll say: “But we love each other, why can’t we make this work?”
Love is powerful, but it’s not always enough to withstand the storm that untreated depression, anxiety, ADHD, trauma, or other mental health conditions can bring into a partnership.

• Depression may look like emotional withdrawal, disconnection, or irritability.

• Anxiety may manifest as controlling behaviors, constant worry, or feeling “on edge.”

• ADHD may be misunderstood as aloofness, carelessness, or even anger.

• Trauma may show up as shutdowns, avoidance, or emotional flooding.

These patterns don’t just impact the individual—they ripple into the relationship. Without support, couples often misinterpret symptoms as disinterest, rejection, or even incompatibility.

Why Couples Avoid Naming It

In my work with couples in Miami, I’ve seen how stigma around mental illness keeps partners silent. Too often, there’s still a fixed idea of what someone with mental illness “looks like” or “acts like.” When a partner doesn’t fit that stereotype, it’s often easier to project the challenges onto the relationship rather than looking inward.

Other barriers also play a role—like the lack of access to culturally sensitive mental health care or the fear of being labeled as “broken.” But ignoring mental health struggles doesn’t make them disappear. In fact, avoiding them only allows resentment, misunderstanding, and distance to grow.

When Therapy Needs to Be a Team Effort

When mental illness is present, couples therapy often works best as a blend of joint and individual sessions. Sometimes, I’ll also recommend outside referrals for additional support.

For example, Jordan and Rene see me for couples therapy. Alongside our work together, I might refer Jordan to an individual therapist specializing in combat trauma to address PTSD symptoms, while I meet with Rene individually to help her manage social anxiety. At the same time, we continue building their relationship skills in our joint sessions.

It’s crucial for partners to understand the diagnosis, triggers, symptoms, and treatment plan. When partners have this knowledge, empathy grows and they can make conscious choices to respond differently. This is why joint sessions remain essential—and ideally, if additional therapists are brought in, everyone collaborates closely so the couple receives consistent, aligned care.

This layered approach ensures that both the individual and relational needs are addressed, creating a stronger foundation for long-term healing.

The Cost of Silence

When left untreated, mental illness can:

• Create cycles of conflict that never seem to resolve.

• Lead to emotional burnout for both partners.

• Erode trust and intimacy.

• Fuel hopelessness about the future of the relationship.

This is often when couples say, “Maybe we’re just not meant to be.” But the truth is, it’s not necessarily incompatibility—it’s untreated mental health challenges that have gone unspoken for too long.

Breaking the Cycle

Seeking professional support as a couple doesn’t just mean learning how to communicate better—it can mean:

• Identifying when a partner is struggling with mental illness.

• Creating strategies to support one another without enabling unhealthy patterns.

• Working as a team with individual therapy, psychiatry, or other supports.

• Building resilience so love has space to flourish, even through the hard seasons.

Couples who lean into this work often discover that their love is stronger than they realized. With the right tools and support, they don’t just survive—they grow.

A Note on Heartbreak Recovery

Sometimes, couples don’t seek help until it’s too late. In my work as a therapist, I’ve also supported individuals navigating heartbreak recovery after relationships ended—not because the love wasn’t there, but because mental health struggles were left unaddressed. Healing from that kind of loss takes time, compassion, and often a reframing of what really happened.

Final Thoughts

If you and your partner are struggling, don’t wait until things feel unfixable. Relationships don’t fail because of love alone—they often struggle because pain went unnamed and untreated. Mental illness isn’t a flaw; it’s a reality many people live with. And when couples face it together, they give their relationship the best chance to thrive.

✨ If you’re in Miami or anywhere in Florida, and you’re ready to do the work, therapy can help you break the silence and start building a healthier, stronger partnership.