"When I was a little girl, my birth dad always called me his 'little partner' – something that might've sounded strange without his southern cowboy-like accent.
"To me it made perfect sense. And today that word makes perfect sense again but today I'm officially going to be someone else's partner."
She added: "@maxehrich – I knew I loved you the moment I met you.
"It was something I can't describe to anyone who hasn't experienced it firsthand but luckily you did too. I've never felt so unconditionally loved by someone in my life (other than my parents) flaws and all. You never pressure me to be anything other than myself. And you make me want to be the best version of myself. I'm honored to accept your hand in marriage. I love you more than a caption could express but I'm ecstatic to start a family and life with you. I love you forever my baby. My partner. Here's to our future!!!! (sic)"
The pair's romance was first confirmed when Demi - who previously dated model Austin Wilson - accidentally crashed Max's Instagram Live session.
And sources later revealed that they had decided to quarantine together at Demi's house amid the Covid-19 pandemic.
An insider said in March: "Demi and Max have been seeing each other for a few weeks now. They have been quarantining together at Demi's house and it's going really well.
"Max is very into music and health, and he doesn't like to party. He is a good influence on Demi and they have a lot in common. They have a few mutual friends in common, but Demi has been introducing Max to her closest friends via Facetime since being quarantined. It's very new but they are definitely hanging out and seeing where it leads."
Just last month, Demi gushed that she feels "unconditionally loved and accepted" by Max.
