Demi Lovato decided to break up from Wilmer Valderrama because she has "never been alone"

She said: "The sparks never faded but there are issues that I haven't conquered yet that I know I won't conquer if I'm relying on somebody else to take care of the loneliness. I just wasn't ready and there was so much in my life that I hadn't explored yet ...

"That was one of the reasons why we broke up because I've never been alone. It had nothing to do with falling out of love, we decided together we just probably are better as friends."

The 25-year-old singer admits she has "never loved anybody" like she loved the 'That '70s Show' actor.

She added: "I've never loved anybody like I loved Wilmer and I still love him. I met him on Jan. 11, 2010. I thought 'I have to have him,' but I was only 17 and he was like, 'Get away from me.'

"When I turned 18, we started dating. I think it was love at first sight, we connected on a level that I've never connected with anybody before, he was just my rock, my everything."

Demi has confessed there are times when she wonders if she did the right thing, deciding to let Wilmer go.

Speaking in her Simply Complicated documentary, she explained: "I do have moments where it's late at night and I'm lonely and I wonder if I made the right decision because love is a gamble. I don't know if I'll lose him for the rest of my life. I think my heart is always with Wilmer, I think it was with Wilmer, I think it is with Wilmer, I think it will be.

"Because you don't share six years with somebody and not give them a piece of your heart and vice versa. I'm pretty sure that I'm not going to meet anybody that compares to him but I'm trying to keep an open heart and open mind when it comes to that."