Dos and Don’ts of Dating Someone Who’s Already in a Relationship

Emma Blake
5 days ago
4 min read

Falling for someone who is already in a relationship can feel like stepping into an emotional maze—thrilling, confusing, and sometimes terrifying. Whether you are exploring ethical non-monogamy, polyamory, or dating someone in an open relationship, navigating this kind of romance requires a unique set of skills, emotional intelligence, and deep self-awareness.

The key to making it work? Understanding boundaries, communicating clearly, and knowing what’s healthy versus what’s destructive. There’s a right way to love someone who is already in a relationship—and plenty of ways to do it wrong.

But sometimes, even when you follow all the "rules," love can still hurt. I learned that the hard way.

A Personal Story: When Love Isn’t Enough

I never expected to fall for someone who already had a partner. But love doesn’t ask for permission. It just happens. When I met Alex, he was honest from the start—he was in a committed open relationship with his girlfriend of five years, Sarah. He assured me that she knew about me, that their relationship was built on trust, and that he had space in his life for another love.

For a while, it was beautiful. I felt seen, cherished, and respected. We had late-night talks, weekend getaways, and a connection that felt deeper than anything I had known before. But as time went on, reality sank in. There were birthdays I wasn’t invited to. Holidays where I spent the evening alone, knowing he was with her. Times when I wanted more, but he had already given all he could.

The worst moment came when Sarah, despite agreeing to non-monogamy, confessed to Alex that she wasn’t as comfortable with it as she had claimed. She asked him to prioritize their relationship and take a step back from me. And just like that, I became a choice he had to make. And he didn’t choose me.

I spent months questioning what I had done wrong. Was I selfish for wanting more? Was I naive for believing I could handle this? Eventually, I realized that love—no matter how strong—isn’t always enough. Timing, boundaries, and emotional capacity matter just as much as feelings do. That heartbreak taught me the most valuable lessons about non-monogamy, self-worth, and the importance of honoring my own needs.

If you’re entering a relationship with someone who’s already committed to another person, know this: You deserve love that doesn’t leave you feeling like an afterthought.

The Do's of Dating Someone Who’s Already in a Relationship

1. Do Understand Their Relationship Dynamics

Before diving in, take time to understand the existing relationship structure. Not all “open” relationships mean the same thing.

Are they practicing polyamory, ethical non-monogamy, or relationship anarchy?
Do they have a primary partner or a hierarchical system?
Are there established rules or agreements between them and their existing partner(s)?

Respecting these dynamics from the start prevents misunderstandings and ensures that your relationship aligns with everyone’s expectations.

2. Do Communicate Honestly and Frequently

Open relationships require radical honesty. Unlike traditional dating, where some emotions or insecurities might be brushed aside, non-monogamous relationships demand clear, ongoing conversations.

Express your needs and boundaries early.
Check in regularly about emotions, expectations, and comfort levels.
Be transparent about your own feelings—whether it’s joy, jealousy, or uncertainty.

Good communication isn’t just important—it’s everything.

3. Do Respect Their Time and Priorities

When dating someone who’s already in a relationship, understand that their time is shared. They have commitments, schedules, and emotional responsibilities to another person.

Avoid expecting last-minute plans.
Be flexible and patient with scheduling.
Respect their existing commitments without making them feel guilty.

Understanding this dynamic makes you a supportive and compassionate partner.

4. Do Establish Boundaries for Yourself

Just because you’re the additional partner doesn’t mean you shouldn’t have boundaries of your own. Ask yourself:

What do I need to feel secure in this relationship?
Am I comfortable with limited availability?
What level of emotional connection do I want?
How do I handle feelings of jealousy or insecurity?

Setting personal boundaries ensures that you’re entering this relationship in a way that aligns with your values and emotional well-being.

5. Do Build a Relationship with Their Primary Partner (If Appropriate)

In some ethical non-monogamous relationships, meeting and building trust with your partner’s existing partner(s) is encouraged. This isn’t about seeking approval—it’s about creating a sense of transparency and reducing misunderstandings.

Some polyamorous relationships thrive on a sense of community.
Other relationships prefer keeping partners separate.
If introductions are encouraged, approach with respect and openness.

Never force a connection, but if it feels right, mutual understanding can help eliminate jealousy and tension.

The Don’ts of Dating Someone Who’s Already in a Relationship

1. Don’t Expect Them to Leave Their Partner for You

This is one of the biggest pitfalls. If someone is in an open relationship, it means they have already chosen to love more than one person.

Avoid entering the relationship hoping they will leave their partner.
Accept that they love their existing partner(s) and that doesn’t diminish their love for you.
Recognize that non-monogamy isn’t a “transition phase” to monogamy.

If you find yourself wanting exclusivity, reconsider whether this dynamic is right for you.

2. Don’t Disrespect Their Existing Relationship

Your connection is valid, but it doesn’t override the existing relationship. Respect is non-negotiable.

Don’t trash-talk their partner.
Don’t push them to break relationship agreements.
Don’t try to “one-up” their primary partner.

A relationship built on mutual respect stands a better chance of thriving.

3. Don’t Ignore Your Own Emotional Needs

It’s easy to get swept up in the excitement of a new relationship, especially in non-traditional dynamics. But if your needs aren’t being met, don’t ignore the warning signs.

Ask yourself:

Am I feeling neglected or undervalued?
Is this relationship making me happy in the long run?
Am I suppressing emotions just to “make it work”?

A healthy relationship—monogamous or not—should bring you joy, not emotional exhaustion.

Love with Awareness, Respect, and Intentionality

Dating someone who’s already in a relationship requires self-awareness, open communication, and emotional intelligence. It’s not about being “the other person”—it’s about building a connection that respects everyone involved.

By following these dos and don’ts, you can create a relationship that is fulfilling, drama-free, and based on mutual respect. Whether you are new to ethical non-monogamy or an experienced polyamorous dater, always prioritize honesty, emotional well-being, and the dignity of all involved.