The singer and reality TV star started dating the 23-year-old medical student in July, and has described her as "amazing".
"Before, I was dating and going out and having fun, but I felt empty," he told The Sun. "Very early on in our relationship, I felt that gap had been filled - this is the happiest I have been in years.
"Emily's amazing. It's still early stages and it's going great so I don't want to jinx it. But I miss her when I'm not with her.
"I just love spending time with her. She is my breath of fresh air. And I've always wanted to remarry, settle down and have more kids."
Andre also revealed that a track on his new album Angels and Demons is inspired by his new partner.
"'Fly Away' is all about Emily. That song is exactly about us. The only things I have done that are personal are the positive things.
"This album is about taking the control back and I have done it with my own label. I didn't want to sound like anyone else and I do regret releasing some singles. They were good albums but at times I was doing songs I didn't really like."
Peter Andre recently revealed that he has cancelled plans to spend his 40th birthday with friends in Las Vegas in order to stay at home with MacDonagh.
Watch the video for Andre's new song 'Bad As You Are' below: