Dear Katherine,

I’ve been married to an amazing lady for the past five years. However, I’ve now got to contend with my sister-in-law on a regular basis, who is recently divorced. She is a few years younger and is completely opposite in personality, style, sexuality and poise compared to my wife. In my opinion her divorce has allowed her to become a different woman, so much more free, sensual and sexy that it’s got me in awe.

We often end up going out clubbing together, and sometimes she’ll cling onto me and be a huge tease in the club. She becomes a fantasy. I get to see her in various situations, like seeing her topless in her parents room while I’m walking past, or seeing her strut in skimpy lingerie in front of me while we’re on vacation.

I’ve reached a boiling point now. Each time she exposes herself to me in a different way, she tries to get me to enjoy or see a different part of her body. It’s so easy, too, because none of the family actually sees this or even thinks something is wrong. The issue also is that because she knows she’s so hot, she kind of tests my reaction.

What do you think will be the ultimate setup or test to see if there is more to this? I’ve tried in the past, and she was so willing to cut her dates short just to meet me. I know it’s wrong, but these opportunities are rare. I’ve just had too many weird experiences where she comfortably grabs my attention with family around. I hope you will be able to guide me to the right choices.

Thank you,

My Dearest,

To be inspired by another person’s sensuality is wonderful. To be enthralled to their independence, sexiness, beauty and witness them undergo a transformation to becoming themselves is a wonderful thing. Here’s what isn’t wonderful—cheating on your wife with her sister.

Familial environments create feelings of intimacy. People feel safe so they become less inhibited in their actions and words. Sometimes this causes behavior and subsequent attraction, which out in the world would happen and then pass without much thought, but in the context of a home and regular contact has a way of recurring. Unwarranted and inappropriate attraction can be a natural—yet dangerous—byproduct of a safe space like a home.

I have a number of opinions about this situation, but the most salient one is: Don’t have an affair. Because, in fact, it’s already not what you want. You have a pre-existing relationship with this woman, your wife’s sister, so it couldn’t possibly be a casual fling as you seem to believe it could. Plus, your wife will probably find out. Especially if she is, as you say, an amazing lady.

To assist you in your quandary I’ve turned to a literary genius and top-notch asshole, Ernest Hemingway. I feel that he is able to speak to the perils and joys of infidelity best. As he would say, “Courage is grace under pressure.” You’re going to need a lot of both for the kind of pressure you’re under.

Remember It’s a Good Thing Hemingway writes in A Moveable Feast: “When you have two people who love each other, are happy and gay and really good work is being done by one or both of them, people are drawn to them as surely as migrating birds are drawn at night to a powerful beacon.” I bet you and your wife have a good thing going on. And I bet that’s why your sister-in-law feels comfortable expressing herself around you both. She probably, to a certain degree, feels safe and is drawn to you like some kind of “beacon.” With that knowledge, think about how your attraction to her may in fact be contingent upon the strength and safety of the relationship you’re already in.

Examine the language about Temptation Ugh, I get it. Temptation feels great. Bikinis, stolen glances, the club. It sounds like fun. However, I’d caution you in your assumption that your sister-in-law is doing this on purpose. Hemingway describes the following situation: “An unmarried young woman becomes the temporary best friend of another young woman who is married, goes to live with the husband and wife and then unknowingly, innocently and unrelentingly sets out to marry the husband.” He calls such a series of events “the oldest trick there is.” Sound familiar? I’d argue your sister-in-law’s actions aren’t “trickery,” necessarily. Rather, I’d guess that even though her sensuality is aimed at you right now, it has a lot more to do with a personal process of discovery. That tends to happen post-divorce. You may simply be caught in the crossfire. Keep that in mind as you proceed, and don’t assume she’s doing what she’s doing simply to torture you.

Spend Less Time Around Her This is pretty basic. You can elect to spend your time how you want. Make yourself scarce when she’s in town. Make other plans. Hem seemed to revel in solitude. “Alone there was no problem when you got used to it.” I totally agree with him here. There’s nothing like a little solitude to help you get your head screwed back on straight and to prevent you from screwing the wrong people.

Have a Frank Conversation With Your Wife Hemingway famously once said, “The best way to find out if you can trust somebody is to trust them.” I’m so glad you wrote me when you did because I have the chance to ask you questions before you make any moves. Are you invested in your relationship with your wife? Do you want her to trust you, and do you want to trust her? If the answer is yes, I suggest you broach a conversation with her about your attraction. Approach the topic with delicacy and a desire to re-affirm a relationship with her. If no part of you wants that with your wife then get out. Now.

Have a Frank Conversation With Her Sister NOTE: Do this AFTER you have a conversation with your wife. Discuss her behavior and yours in relation to it in an effort to set boundaries and forge ahead with mutual respect. Do this in daylight and sober.

Have a Frank Conversation With Yourself Remember how I was telling about what Hemingway calls, “The oldest trick there is”? He wrote more about that. He says of his experience being torn between two women, “You lie and hate it and it destroys you and every day is more dangerous, but you live day to day as in a war.” Sound fun? Didn’t think so. Ask yourself what you’re seeking that you’re not getting in your marriage. If it’s hot sex and danger, is it really worth it to you to jeopardize your life with an amazing woman? Is there a way to accommodate those needs with honesty in the context of your relationship? Ask yourself the big questions now before you make any big moves.

Part of the reason I turn to old Ernie is because of his simultaneous ability to describe beautifully the feeling of illicit attraction and the reality of the fact that he had a pretty messed up and unhappy life. Your feelings of attraction are neither wrong nor unfounded, but how you negotiate them is what counts.


Just the Tips is’s weekly advice column with professional matchmaker Katherine Cooper. Have a question for Katherine about sex, love or dating? Shoot her a note at or follow her @kathkathcoop.