The 90210 beauty first started romancing the Prison Break actor in 2011, but the couple split in December, 2014 after three years together.
They sparked rumours of a reconciliation last summer (15), and now AnnaLynne has revealed they fell back in love as she supported the 46-year-old through his health crisis.
"I came back into his life as his friend, and I took him to his doctor's appointments and I was there with him because whether or not he realised it, I love him," the 28-year-old recalled on the Allegedly podcast with Theo Von and Matthew Cole Weiss. "One of the things he said was, 'You really love me, don't you?' I was like... 'Oh my God. Are you kidding me? Are you kidding me? After all this time, you still don't know that? I gave up all my 20s for you!'"
AnnaLynne and Dominic are now enjoying life as a couple again, and she couldn't be happier.
"I'm very happy, I have my best friend back, so it's cool," she smiled.
The actress also touched on the problems which had originally driven the stars apart, revealing Dominic had struggled with trust issues in the past, particularly with women who took advantage of him and assumed he was "not intelligent because of how he looks".
But AnnaLynne insists Dominic is so much more than just the tough guy characters he portrays onscreen.
"One of the things that's sexiest about him is how incredibly intelligent he is, and well read, and prolific and a big thinker," she gushed.
However, the blonde star is in no rush to marry - although she wouldn't turn down a proposal if her man did pop the question.
"For me, I like the idea of taking your time with things," she explained. "Clearly, we're not going anywhere. There's a lot of pressure from everyone in the world."
"If the question is asked, I will definitely say yes," AnnaLynne admitted. "I would love to just let life happen... I'm not pushing back on it, which I used to do... I'm open to it, we're not there yet. But, you'll be the first to know!"
AnnaLynne previously dated Twilight star Kellan Lutz, while Dominic was married to film producer Rebecca Williamson, the mother of his four children, from 1998 to 2008.