We seriously have no idea how this relationship is legal!

Teen reality star Kylie Jenner and her 25-year-old boyfriend Tyga jetted off for a vacation to France on Tuesday. The inappropriate duo is set to touch down in Nice, France, later tonight. The 17-year-old is joining older sister Kim at the Cannes Lions festival in the South of France.

These two seem to be getting serious about each other -- maybe Tyga will marry the teen sensation, then have a kid with her and ditch her -- just like he did to Blac Chyna. Wouldn't that be adorbs?!

We guess we know what Kylie was shopping for when she went to Agent Provocateur over the weekend -- a little treat for Tyga on their trip! Gross.

Apparently Tyga is happy to get in there while they're still young. Kylie turns 18 on August 10. Let's hope that once she's legal Tyga doesn't kick her to the curb for a younger model, on second thought (for Kylie's sake), let's hope he does ...

We have no idea why Kris Jenner is cool with this relationship -- but she is the woman who trained the members of the Kardashian Klan to be the way they are today, so we kind of aren't surprised that these two are about to jet off to a family holiday together.