Dear Carolyn: I have a close friend I want to understand. “Carla” is a college-educated and successful registered nurse. We tried dating early on, but her ex-boyfriend, “Dylan,” kept harassing us. Dylan suffers from depression and is a recovering alcoholic. If we went to church, Dylan was in the pew behind us. If we went to a restaurant, he mysteriously showed up. One day, Dylan appears arm-in-arm with a new woman and announces that he and Carla are history. Carla bursts into tears and leaves. She later tells me she dated me to make Dylan jealous!

It gets worse. Carla soon starts seeing “Justin,” who is bipolar, legally separated, and even worse than Dylan. Carla says Justin reads her e-mails, checks her cell-phone calls, and calls or visits daily where we work. Carla is clearly unhappy, and has resorted to using colleagues’ cell phones to call family and friends. Our friends say I should try again with Carla, but I feel it wouldn’t work; while I would never treat her like these two have, I would be someone she settled for. I do wonder how someone so otherwise intelligent can consistently pick the wrong guy.

— Atlanta

Dear Atlanta: No no no. Carla is picking exactly the right guy, to give her exactly what she needs.

You made a common leap; people do tend to assume that everyone wants to pair off happily ever after. From there, it’s not hard to conclude that someone unhappily paired just needs to find a more suitable mate.

But think about it. Some people who need a hobby take up knitting. Others take up bungee jumping. Brains are different. Emotional makeups are different. The ways we find and feel pleasure are different.

The way Carla finds and feels pleasure is, apparently, through emotional bungee jumping. Is this smart? No. Healthy? No way. But it’s what Carla does.

That means: (1) You’re right that you and Carla wouldn’t work as a couple, and (2) You’re off about why. Your taste in pseudonyms notwithstanding, you’re not a bad enough boy to star in her daytime drama; at best you can pitch in as foil.

People concerned about Carla would do well to think less of boyfriend upgrades and more about her emotional health. Whether her choices stem from illness, past abuse or garden-variety family dysfunction, she needs to start treating the cause before she sinks deeper into a relationship that already, with Justin’s spying, looks to have crossed the line into abuse. Carla can’t help herself until she recognizes she needs to, but maybe that’s where her friends — the ones without a romantic agenda — can step in with judicious suggestions.

Speaking of rescues ... with Carla’s hideous behavior toward you, and your unabated admiration for Carla, you might want to tug at your own sweet tooth for theatrics. “Carla” and “Dylan” and “Justin,” oh my.

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