Author Emily Giffin. (Photo by Michael Loccisano/Getty Images)

Over her last decade of writing relationship-themed novels, best-selling author Emily Giffin has explored every dramatic situation you can imagine: A woman who sleeps with her best friend’s fiance in “Something Borrowed.” A doctor who cheats on his wife with his young patient’s mother in “Heart of the Matter.” A teenager who gives her baby up for adoption and never tells her boyfriend she was pregnant in “Where We Belong.”

Her new book, “First Comes Love,” also deals with complex marriages and dating scenarios, but it tackles the toughest kind of relationship: the one you have with yourself.

“My earlier books tend to be more about finding love, and this one is more about finding your way in life and deciding what’s best for you,” Giffin said recently by phone from Atlanta, where she lives with her husband and three children. “The book is very much about you making your life what you want it to be.”

“First Comes Love” (already optioned for a film) is rooted in the lives of two sisters, Meredith and Josie. The story starts as their beloved older brother, Daniel, is killed in a car accident. Fast-forward 15 years: They still haven’t fully dealt with the tragedy, which complicates their already difficult relationship. Meredith seems to have the perfect life with her husband and daughter; she tags her Instagram photos #blessed, but she’s secretly miserable. Josie is a free spirit who can’t settle down; in her late 30s, she decides to have a baby on her own.

I talked to Giffin, who will be in D.C. on July 12 for a book event at The Hepburn, about her fascination with writing characters who are tough to root for; if she really thinks men and women can be “just friends”; and the one thing she doesn’t love about the 2011 movie version of “Something Borrowed,” starring Kate Hudson, Ginnifer Goodwin and John Krasinski. Here’s our conversation, which has been edited for length.

You write a lot about difficult romantic relationships. What made you want to write about a difficult relationship between sisters?

I have one sister — she’s my only sibling and 14 months older. My relationship with her has always been one of my most important relationships. I just think it’s such a complicated one, though — because I consider her my best friend, but I don’t know that we would be friends if we weren’t related. That’s the thing about family. It’s a sort of a forced relationship, and in most cases a very special one, but it can be complicated. The people who know us the most are the ones that we’re capable of loving the most fiercely and fighting with the most fiercely.

That theme struck a chord with me because I have a sister, and growing up, we didn’t hang out a lot. But now we’re really close and talk every day. Why do you think some sisters take the leap to being friends as adults and some don’t?

I think that, as we get older, we realize how important our history is, and our sense of family, and you really can’t necessarily have that perspective as a teenager or in your early 20s. I think that grows over time and you become wiser about what’s important. In most cases, we learn to jettison unhealthy relationships or learn to fix them. You often will hear from someone who has either no communication with their sibling, or they’re extremely close.

Another theme in the book is how tragedy and grief affect people so differently. Why did you want to explore that topic? 

I think it was an interesting way to really get into the depth of these two girls and their relationship and how we react to things so differently. Grief is one area where we really see such a wide disparity in how we handle tragedy. Some people want to talk about it, and some people want to just brush it under the rug — and all those different responses, I think, are just so important to understanding who we are as people.

In your books, you often get readers to sympathize with characters who are hard to root for. Both Meredith and Josie have very unlikable moments. How do you walk that line when you’re writing?

One of the things I’ve done in all of my eight books is basically put a good person in a untenable or unsympathetic situation and try to get the reader to root for her in spite of what she’s doing. I think that’s life. Even though we have a sense in our heads and our hearts about what’s right and what’s wrong … when you get into life, it’s about the gray areas. I just love exploring that nuanced terrain, and the guilt and the regret that comes from our mistakes and our weaknesses.

In “First Comes Love,” Josie is best friends with her roommate, Gabe, and they’re both adamant this is a situation where a man and a woman can be best friends with no romantic feelings. Is that based on a real-life situation, or did you want to make the point that men and women can just be friends?

I do believe that! I’ve had such good male friends. And those relationships with guys are so important with me; they’re so unique and different than the female friendship.

In “Something Borrowed,” Ethan and Rachel were friends, and that was the one thing that I argued with, that I really debated strenuously with the producers of the movie version. I so much didn’t want Ethan (Krasinski) to confess his love for Rachel (Goodwin) at the end, because I believe that friendship was just very pure and there was no undercurrent of romance.

Josie eventually decides to have a baby through a sperm donor. For that story line, did you do a lot of research about people who take that path?

I typically don’t research emotion — so I didn’t think to myself, “Okay, I need to talk to women and their sense of urgency over having a baby.” I can imagine that. I wanted children more than I wanted a husband. And I know that if I were 37, 38, and I hadn’t found someone I wanted to spend my life with or to marry, I’m certain as I can possibly be that I would have chosen this route. I would have either gone with a friend or I would have done it by anonymous sperm donor. I did research how the process works — all the mechanics, in other words.

You also frequently write about anxiety over becoming a mother: Darcy’s accidental pregnancy in “Something Blue”; Claudia faces judgment when she doesn’t want kids in “Baby Proof”; and Marian gives her baby up for adoption in “Where We Belong.” Are there just endless amount of avenues to explore?

Absolutely. I think part of writing about relationships is writing about all the choices that come with relationships and the fact that things aren’t black and white. I love exploring unconventional relationships … that wouldn’t be what you would choose for yourself when you’re younger and mapping your life out. I used to say, “I want to have a baby girl and then a boy and then a girl.” A lot of us do that, particularly women.

I feel like we’re doing it less and less as time moves on, because my mother’s generation was so traditional that I think they passed along some of those things to us — like, look for a husband, and what your wedding is going to be like. That’s shifting, and there’s more acceptance for different paths. And the people who are open to their own version of happiness are the ones that are the happiest.

So, what’s the status on the rest of your books becoming movies?

[Laughs] “Something Blue,” I know it’s driving people crazy, but the script is in such great shape and it’s definitely going to happen. We’re moving forward, we’re sending the script to Kate [Hudson] and John [Krasinski] soon, and I think that’ll be in production in the next year. “First Comes Love” is being optioned. We’re finalizing the contracts right now.

READ MORE:

The line that divides me from my friends: They have kids and I don’t 

I got sober for myself. Then I found love on Tinder.

LGBTQ and heterosexual weddings have a lot in common, survey finds