No matter how old you are or how you meet, finding a best friend is like falling in love.

Your heart opens when you discover someone you want to know for the rest of your life. It's the two of you against the world, and now that you've found each other nothing can stop you.

Then your best friend falls in love for real. Of course you want her to be happy, but suddenly it's not just the two of you anymore. There's this third person who's always around that you didn't choose. So what if you really, really hate her choice?

You don't want to lose your friend, she doesn't want to lose her partner, and her partner sucks. It's a scenario that can make or break a friendship. In order to move forward, you have to navigate the situation very carefully. Before you confront her about her relationship, you need to confront yourself. There are a few key questions that will help you decide what to do next, and ultimately, keep your friendship intact.

Real talk: Are you feeling a little threatened?

Before you say or do anything, you need to check yourself. There's a chance it's not your friend's partner, it's you.

When your best friend falls in love, your whole friendship dynamic shifts. At first, you might feel a little threatened that this new person will replace you. And maybe in the beginning, you're not entirely wrong. She's not around as much, she obsessively talks about how amazing her partner is. Eventually, she'll get over the infatuation and you'll adjust to the new person in her life.

If you feel the need to confront her, don't make it about her partner. Tell her you miss her, and set up some one-on-one time to try something new together that will take both of your minds off her SO for a while, and get you back into your friendship groove.

Is her partner really that bad?

Your friend's SO may not be someone you'd choose to have in your life, but your friend is. And if you want to keep her around—and deepen your friendship— you may have to keep an open mind. The more you convince yourself you don't like her partner, the harder it will be to accept their relationship in the long term.

"Our brains look for information that supports our thoughts and beliefs," Eileen Purdy, MSW and anxiety therapist tells Bustle. "When you don't like someone or something your brain is then 'programmed' to find examples to support this. And it will do that by leaps and bounds! Recognize this bias exists in everyone and challenge yourself to see the person in different ways."

Maybe this person isn't as funny or ambitious as your friend, but they might nourish other really important aspects of her life. Search for qualities you may have overlooked, like stability, kindness and loyalty.

"If you don't like this person, that's fine. But don't continue to look for evidence," Dr. Linda Carroll, a psychotherapist, tells Manrepeller. "Allow yourself to see that they're bringing joy to your friend and it's not for you anyway. Allow yourself to be open to changing."

How long have they been together?

If their relationship is new, you probably don't want to intervene. Firstly, your friend's infatuation might not last and your honesty about her partner will only make her feel judged. That can cause a real fissure in your friendship, even after her romantic partner is out of the picture. Another reason to hold off on saying anything negative in first few months? Science.

Love is an actual drug that messes with our brains. In those first three months, everything from oxytocin to dopamine flood our heads with pleasurable feelings and bond us to our partners in a way that chemically overrides any rational thought processes.

"We don't see red flags ourselves and we don't want to hear about them because we want the fix," Dr. Carroll tells Manrepeller. That means any judgements you share with your friend about her SO is going to fall on dead ears. "Your information is not going to be welcome," she adds. "They can't hear it."

If their relationship persists after this initial period, revisit question one ("Is her partner really that bad?"). The more you get used to their dynamic, the more your own feelings might shift from hating it to appreciating how happy it makes her feel.

"We've all known people that feel one way about someone and then a year later see them a little differently," Deb Owens, a Philadelphia-based therapist, tells TheCut. "So you always want to leave open the possibility that a viewpoint could change."

Is your friend in real danger?

There are, of course, exceptions to the wait-it-out rule.

"If you think her relationship is endangering her health or emotional well-being, do whatever you have to do to help your friend, whether that means getting her parents (or other family members) involved or staging an intervention with a few other close friends who can back you up," writes Irene S. Levine, PhD, professor of psychiatry at New York University School of Medicine, on TheNest. "It's okay to be judgmental when the stakes are high and the problem is serious."

It's crucial to approach your friend with love and respect rather than judgement. One way to do that is to ask her questions so she can hear her own concerns. Ask her how she feels about herself lately, what concerns she might have in her relationship, and if there's anything you can do for her. This opens the conversation up so you're not just giving her feedback but allowing her to process her own feelings.

If she's not receptive to this line of questioning, therapist Doris Krasnopolsky, LCPC, suggests a more direct approach. "Try instead to talk about the behavior that you are witnessing and give concrete examples," she writes on ThriveGlobal. "Follow this up by expressing what your greatest wish is for her."

The most important thing she needs to know is that no matter what happens, you are there for her. "It doesn't have to be black or white — you can be supportive of her even if you are not supportive of their relationship," adds Krasnopolsky.

Is confronting her worth risking your friendship?

"It's always a risk to stick your neck out unless a friend brings it up first," Rachel Sussman, a Licensed Clinical Social Worker, tells VerilyMag. "You have to remember that once you say something negative about the person he or she may [eventually] marry, your friend may go ahead and marry that person nevertheless and it could negatively affect your friendship."

Maybe her SO isn't that bad. Maybe you'd rather be in your friend's life than risk losing her altogether by confronting her with your opinions. If that's the case, embrace the workarounds that will keep your friendship tight. Set up QT nights where the two of you can be together alone, and do your best to find the good—any good—in her partner.

On the other hand, if your friend's partner is threatening her emotional or physical well-being, risking your relationship in order to help her is absolutely worth it. And there's a good chance, with your support, she'll be strong enough to extract herself from a bad situation, or at least, come to appreciate your concerns and anchoring presence. Be patient and give her time to process the information you provided. If she needs a break from you, assure her you'll still be there when she's ready to be close again. Partners come and go, but best friends are unconditional.