Is 'Sister Best Friend' A Popular Romance Trope?

“You have no idea what you’ve done to me. I’ve been replaying every sound you made, every way you came apart for me.” His grip tightened. “I’m not letting that go. I’m not letting you go. Fuck the friendship. I want you.” I let out a little gasp. His thumb rubbed across my lower lip. “I don’t just want to fuck you—I want to keep you. You’re my favorite sin, and I’ll commit it again and again until you understand you’re mine.” His lips twitched a little. “You’ve always been mine, Savannah.” ——- Her sister is marrying her ex. So she brings her best friend as her fake fiancé. What could possibly go wrong? Savannah Hart thought she was over Dean Archer—until her sister, Chloe announces she's marrying him. The same man Savannah never stopped loving. The man who left her heartbroken… and now belongs to her sister. A weeklong wedding in New Hope. One mansion full of guests. And a very bitter maid of honor. To survive it, Savannah brings a date—her charming, clean-cut best friend, Roman Blackwood. The one man who’s always had her back. He owes her a favor, and pretending to be her fiancé? Easy. Until fake kisses start to feel real. Now Savannah’s torn between keeping up the act… or risking everything for the one man she was never supposed to fall for.

Isabella Martinez is a Smart and Shy Teenage Nerd who is very unaware of how attractive she is. The return of her Best friend’s brother and next door neighbor, Bradley Johnson brings an overturn of issues and a spiral of long buried emotions from Bella. Asides from Brad’s wrongful action towards Bella in the past, she has promised her Best friend Olivia, never to have anything to do with Brad. However, the sizzling Chemistry is undeniable. Secrets are about to be kept and promises broken!! Will this forbidden romance be able to survive?

He is a 10 but he is a decade older than me, my brother’s best friend, a therapist who wants to counsel me and... he likes to hurt little girls like me. “What were you doing this morning?” “I was meditating.” He is right. I am a terrible liar. Aiden raised his eyebrows. “Is that so?” He waited for my answer, crossing his arms over his chest. I got distracted by the way his biceps bulged. He noticed me staring. I glanced down at my lap, twiddling my thumbs. “Y-yes, Doctor Aiden, I was meditating and I-I focused on my breath like you taught me—” “Why are you lying to me, Ivy?” My head snapped at him. “I-I am not lying.” Aiden tilted his head and my throat went dry when he said, “Then why did I hear your voice moaning my name when you orgasmed with your fingers inside you?" He is her first love. She is his best friend's little sister. Will a chance reunion lead to true love? I was a good girl. An honor student. A dutiful daughter, sister and a sweet girlfriend to my boyfriend until I found him in my best friend’s bed. I didn’t want goody-two-shoe nice boys who gave me empty promises. What I wanted was a man who wouldn’t hurt me. When I found my brother’s best friend, Aiden Stone, with only a towel around his hot Greek body dripping wet from a shower, I decided that what I wanted, what I had been wanting for years, was him. The only problem? He is a decade older than me, my brother’s best friend, a therapist who wants to counsel me and... he likes to hurt little girls like me.

"I want you to take my virginity," I tell my best friend. He chokes on his drink. His eyes go wide, blinking at me like he misheard me. "Dawn." "Not now, obviously. Just promise me you won't let me turn twenty still a virgin," I say, biting my lower lip. He stares at me like I just sprouted two horns. His eyes move slowly across my face. His lips part. He says nothing. "Dawn," he whispers like a plea. For so long, I have loved him. I wanted all my firsts to be his. Instead, I end up in his brother's bed. Killian. I should stay away from him. I shouldn't want him. Not only is he cocky, arrogant — he's the bane of my existence. Yet when he touches me, it feels like I'm the most precious thing in his life.

My best friend had one rule: stay away from my brother. But what he didn't know was that his brother kept me up all night. Wren Mercer had spent years being just Ross's best friend. Fine with holidays at the Calloway house, years of watching Dani, Ross's older brother, move through life like nothing could touch him, fine with the fact that he never once looked at her like she was worth the trouble. So she did what any sensible girl would do, she found someone else. Blake Hendrix was everything that made sense on paper. Charming, attentive, and most importantly, not Dani Calloway. She told herself it was moving on. She told herself it was working. What she didn't know was that Blake had his own reasons for getting close to her, ones that had everything to do with the brother she was trying so hard to forget. When Ross invites her to move into their off-campus apartment, she tells herself it's still fine. She has Blake. She has a plan. Dani barely registers her existence anyway. She can handle proximity. She's wrong. Because Dani does notice her. He always has. What starts as tension becomes stolen moments, a secret neither of them planned, and the slow terrifying realization that this is the most real thing either of them has felt in years. But Ross is right there. Blake is closer than she thinks. And secrets don't stay hidden forever. She fell first. He fell harder. And what breaks between them might not be fixable.

Dylanne Hayes has always had a huge crush on her best friend's brother, Kai. He's every woman's dream, and hers since she was 18. Now Kai is back in the States. He's different, more charming, and she swears she's over him, even after she's required to work with him at work. Work is supposed to be easy, but not with Kai Reed in the picture. Can she resist him this time or betray the promise she made to her bestie?