Los Angeles - Kylie Jenner and Tyga are "totally in love".
The reality TV star and the rapper have been romantically linked since he split from Blac Chyna - the mother of his two year old son King - in 2014 but have never confirmed their romance.
However, they have put on an affection display on their trip to Punta Mita, Mexico, to celebrate Kylie recently turning 18 and sources say she and Tyga, 25, are serious about each other.
A source told Us Weekly magazine: "She and Tyga are very serious. They're totally in love."
Tyga even surprised Kylie with a white Ferrari 482 Italia, worth $320,000, at her milestone birthday party and onlookers said the pair looked smitten with each other.
One eyewitness said: "He was a very doting boyfriend. He was taking her photos for her, leading her around the bar. The family was really spoiling Kylie. You can tell she felt like a princess."
To celebrate the 'Keeping Up With The Kardashians' stars birthday, Tyga posted a sultry image of Kylie on his Instagram page with a message saying: "Happy bday to the dopest girl ever!"