Nikki Reed and Ian Somerhalder are quickly taking their relationship to the next level. Six months after they made their relationship public, the actors are reportedly engaged.

"They're so happy!" a source told People magazine.

Reed, 26, and Somerhalder, 35, were first linked in July after they were photographed together at the Farmers' Market in Los Angeles.

"[Nikki and Ian are] smitten with each other and love spending time together," a source told E! News at the time.

The relationship seemed to heat up quickly as they adopted a horse together in August and recently spent the holidays with family in Sun Valley, Idaho.

Reed's latest romance started just a few months after she filed for divorce from American Idol alum Paul McDonald. The former couple was married for two years.

"After much consideration, Nikki Reed and Paul McDonald are ending their marriage. They have been living separately for the past six months due to work obligations," the actress' rep said in a statement. "They will continue to share their love of music, and are still working on their debut album, I'm Not Falling, releasing in 2014. They remain best friends and look forward to their continued journey together."

Somerhalder was also in a relationship with his Vampire Diaries co-star Nina Dobrev for almost three years before they split last May.

 A day with 3 of the most beautiful ladies in the universe... Wow smiling is such a beautiful part of the human experience-I highly recommend it. Congrats to our little Neitczhe here-1 year ago today, to the minute, you brought 5 beautiful puppies into this world-thank you for your amazing contribution to all of our lives. However, welcome to the wonderful world of being spayed-The world does not need any more puppies, we kill millions and millions per year. These two beautiful creatures right here in this photo or highly intelligent, highly emotional and capable of more love than you can you can ever imagine. The ones that are in shelters are the same-let's adopt them. @iamnikkireed your recent work with Gilt benefiting the @aspca is truly truky extraordinary. Thank you for giving so much of your life and for being a strong voice for those whom can speak. My hat is off to you. You amaze me. Love, Ian

Uma foto publicada por iansomerhalder (@iansomerhalder) a Out 8, 2014 at 1:11 PDT

Tags: celebrity couples ian somerhalder Nikki Reed