When my friend finally found a girlfriend, I was happy for him, but now they can’t stop touching each other. I seriously can’t stand having him over for dinner anymore, because he acts like they’re just on a date. Holding hands or even putting your arms around each other seems OK, but why does she always have to sit on his lap? If not that, she’s stroking his arm, squeezing his knee, or playing footsie under the table. Is this behavior rude or am I just being a kill-joy? Where PDAs (public displays of affection) are concerned, how much is too much? And is there a polite way of asking my friend and his girlfriend not to paw at each other? —The Anti-Cupid

Dear Anti-Cupid,

I once had a friend and his girlfriend to dinner, and all evening long, they played with each other’s hands. Gazing into each other’s eyes, they barely made eye contact with the other guests. I served a chocolate mousse cake for dessert. My friend daubed a little on his girlfriend’s arm and licked it off. I felt like a voyeur.

Couples should avoid making obviously sexual gestures. Not only do they make other guests uncomfortable, they can also make them depressed. Bella DePaulo, author of Singled Out, a book in which she argues that singles are stigmatized, says, “It’s like [the couple] is saying: ‘We’re so madly in love and so sexual.’ It’s offensive in the same way as it would be if someone who worked in finance started bragging about taking home a huge bonus.”

On the other hand, when your friends are in relationships, it’s nice to see a little PDA—an arm around the shoulder, a peck on the cheek, a caress of the hand. It reassures you that people you care about love each other and are happy.

So where do you draw the line? A good question for lustful couples to ask themselves is: Are we paying more attention to each other than to our friends who invited us over? Take footsie, for instance. If someone is gently resting his foot against his lover’s foot, it doesn’t distract the pair from the conversation. But if someone is busy inching her bare toes up the other’s leg, the couple won’t be able to focus on much else.

If you bring it up, the couple may react defensively. Any time you’re hoping to change someone’s bad manners, you should use “I” statements. Make it about you, not about them. For example, you might say: “I feel like I didn’t get enough time with you last night.”

If your friend doesn’t get the hint, you’ll have to put up with his behavior. Just be sure that when you have him and his girlfriend over, you don’t serve anything resembling body frosting.

Table Manners appears every Wednesday. Have a Table Manners question? Email Helena.