The pair had been together for six months.
"It was a tough decision, but Demi and Max have decided to go their separate ways to focus on their respective careers," a source told ET on Thursday. People was first to confirm the split. "They have respect and love for one another and will always cherish the time they spent together."
ET learned that the 28-year-old singer was dating 29-year-old Ehrich in March, after fans noticed the two getting flirty on social media. After a whirlwind romance, the two got engaged in July. A source told ET at the time that the newly engaged couple was extremely happy and in love.
"@maxehrich - I knew I loved you the moment I met you," Lovato wrote on Instagram when announcing their engagement. "It was something I can’t describe to anyone who hasn’t experienced it firsthand but luckily you did too."
She noted that she's never felt "so unconditionally loved by someone" in her entire life.
"I love you more than a caption could express but I’m ecstatic to start a family and life with you," she wrote at the time. "I love you forever my baby. My partner. Here’s to our future!!!"
As for Ehrich, he was equally smitten.
"You are every love song, every film, every lyric, every poem, everything I could ever dream of and then some in a partner in life," Ehrich wrote of Lovato. "Words cannot express how infinitely in love with you I am forever and always and then some. I cannot spend another second of my time here on Earth without the miracle of having you as my wife. Here's to forever baby."
Earlier this month, Lovato celebrated their six-month anniversary with a video of the Young and the Restless star playing with puppies.
"Happy 6 months to my darling, the best father these pups could ever ask for... Thank you for making my life so much better @maxehrich," she shared on her Instagram Story. "I love you baby."
Ehrich shared the post on his Instagram Story as well, writing, "Words fall short, baby. Love you infinitely & then some. Thank you for being the light of my life. Cheers to forever."
For more on their relationship, watch the video below.