Can Having a Mean Sister-In-Law Make or Break Your Marriage?

Despite your best efforts in solidifying your relationship before you tie the knot, there may be one warning sign you've willfully ignored: a mean sister-in-law

Updated 10/23/19

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There may be a myriad of bumps in the road when in comes to marital bliss—think: bringing in boatloads of debt or a desire to have children before your partner. Because you're a super smart bride, we're willing to wager you waded through any potential red flags long before you said "yes." Yet, despite your marriage-savvy ways, there may be one warning sign you've willfully ignored: A mean sister-in-law.

"Having a mean sister-in-law can definitely create strife and conflict between a husband and wife," warns Jane Greer, Ph.D., relationship expert and author of "What About Me? Stop Selfishness From Ruining Your Relationship", "because the most important thing in a marriage is to feel like you're No. 1 to your partner." So while you're vying for your partner's affection and attention, your sister-in-law could be too, "pulling on them to agree with her against [you]," Greer warns. "It's not only hurtful and upsetting, but it can create a lot of distance between a couple."

Not only that, but John Duffy, Ph.D., licensed clinical psychologist and author of "The Available Parent", points out that, "sisters can often be very protective of their siblings. So while I would not go so far as to say a sister-in-law relationship can make or break a marriage, it can often exert an influence as powerful as a mother-in-law or father-in-law."

Take a moment to let that soak in. Because while we've been trained by the media to expect a monster mother-in-law, we're not always prepared to feel resistance from future siblings. But, if your sister-in-law disproves of your upcoming nuptials or simply doesn't like you, you could be in for a roller coaster ride when it comes to your relationship. "Siblings tend to trust one another, sometimes more than they trust their parents or friends," Duffy explains. "The approval of a sibling can weigh quite heavily on a marriage."

There is good news: Not only can you address any sister-in-law issues head-on to ensure your own happiness, but your spouse can also take steps to protect your relationship from your sister-in-law. Over time, with repeated dedication and outward affection toward you, your SO will send a message to your sister-in-law that she will be forced to respect. "The more clarity a spouse has about their love and feelings for his or her partner, the more steadfast they are in the relationship, the more accepting the sibling is likely to be," Duffy explains. By showing your sister-in-law just how much your partner loves you, any ill will she holds toward you may dissipate. "Show a sibling how strong your connection with your spouse is, and how happy he or she makes you," he suggests to your spouse. "It will put her mind at ease."

You can take control, too. While you can and should let some things slide, it's important to stress how her hurtful behavior impacts your well-being and your relationship. "The things you can let go are things like devaluing remarks about your cooking or your appearance," Greer says. "You can shrug these off unless they become so frequent and intense that you feel you need to say something. Otherwise, just ignore her hostility unless it becomes intolerable." Consider also having a private sit-down with your sister-in-law to explain it's upsetting when she speaks negatively about you to your spouse. "Do not allow your sister-in-law to speak with your partner against you."

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