Amber Davies applied for Love Island 2017 to genuinely find love, her sister says.
Speaking ahead of the final, Amber's sister Jade insisted the £50,000 prize fund wasn't a factor.
She told ITV's Good Morning Britain: "I don't think she's got her eyes on the prize at all.
"The money is just a bonus to her. She genuinely went into the villa to find love. I know that is true 100% because she told me."
Jade went on to praise Amber's partner Kem Cetinay but said she didn't imagine them getting serious just yet.
"I'm not sure about marriage and kids," Amber's sister admitted. "Amber is only 20 so maybe that's pushing it a bit far right now – but if they really are in love then perhaps they do need to just go for it.
"He seems like such an incredible and lovely guy. I love Kem. I can't wait to meet him."
Last night's show saw Amber and Kem enjoy a romantic final date.
He told Amber: “Obviously you don’t know what’s going to happen in the future but I’ve gone into it thinking you’re the girl I want to be with.”
Kem explained that his parents knew he can be hard work to deal with: “I’m excited for you to be a part of my life when we leave. I’ve always just done everything on my own and I think that’s why I struggled so much.
"For the first time you kind of rely on someone else’s happiness and I think me getting my head round that, it’s unbelievable.”
They then spoke about their futures before returning to the villa.
In the Beach Hut, Amber confessed: “That was literally the most incredible date I’ve ever been on in my life… We are so young but we’re madly in love with each other, we’re completely obsessed with each other.”
Kem added: “I did not expect to come here and be in love. I’m so lucky, look at her, she has everything and she is perfect for me, it’s the most amazing feeling ever.”
Love Island 2017 continues nightly on ITV2.
The live final airs this Monday night from 9PM.