The pair was spotted at RAWkin' Juice in Burbank, California, on Tuesday afternoon. An eyewitness at the juice bar tells ET that Bieber and Richie definitely acted like a couple when they stopped by around 4:30 p.m.
"He was very engaging with her the whole time, he was very attentive. They were the cutest little couple, there with a bodyguard," the eyewitness notes. "You could just tell they were a couple and he seemed to really care about her."
"They did a taste test of some of the products and he made sure that she was involved," the eyewitness adds. "He walked over and gave her a little cup of the sample. Justin was an absolute doll...I was so distracted by her skin and eyes -- they are amazing."
However, Bieber did not attend Richie's birthday dinner with friends at Koi restaurant. Wearing a black crop top, colorful Adidas pants, and a choker, Richie playfully acknowledged paparazzi, flipping them the bird with a huge smile on her face.
Later that night, she kept the festivities going with a private party at celeb hot spot 1 Oak. Richie Instagrammed videos from her lavish bash, and although she complained earlier on Snapchat about having a rough start to her milestone birthday, it looks like she definitely had a blast. There was no sign of Richie's apparent illness, as she noted that she was "so excited" for the celebration.
"Thank you to everyone who came out last night and made my birthday something special," Richie wrote. "It means the world to have people who will go out of their way to make someone feel special. I'll remember this night for the rest of my life, I love you guys."
While Bieber and Richie were apparently pretty affectionate during their juice date, the 22-year-old "Cold Water" singer doesn't appear to want to settle down anytime soon. Bieber was spotted partying with model Bronte Blampied in London, England, on Friday night at trendy Tape nightclub.