Although both Rihanna and Matt Kemp have made a point of downplaying their relationship, it looks like things are getting serious: Rihanna reportedly flew to Arizona from Berlin, Germany to attend Matt's Ante Up for Autism charity fundraiser. And to meet Matt's family.

A source told E! online:"Matt was happy she came. It was an awesome show of support. Rihanna fit right in as if they all knew each other. It was comfortable."

Matt has a brother diagnosed with autism, so this cause is especially important to the Kemp family.

Sounds like things are getting rather serious, don't you think?

The pictures of Rihanna posing were taken in Berlin, right before she flew back to the States, and the pictures of Rihanna and Matt (below) were taken last January while the couple was vacationing in Cabo San Lucas, Mexico.

Photos by Wenn.com and INF