Sunday night, Kylie Jenner walked the American Music Awards red carpet with Kendall — further fueling rumors that she and beau Tyga had called it quits.But from the looks of the youngest Keeping Up With The Kardashians star's Snapchat, the pair celebrated the rapper's 26th birthday together on Monday night with a custom cake.In her Snapchat video, Kylie is singing the end of "Happy Birthday" and telling Tyga to make a wish before he blows out the candles. (Kris Jenner was also in attendance at the intimate soirée. It looks like she's supportive of this relationship, whatever its current incarnation may be.)