The 38-year-old singer doesn't see the point in tying the knot with the former professional tennis player, whom he has been dating on/off since 2001, because he doesn't think it will better their relationship.
Speaking in an interview with 'CBS Sunday Morning', which will air on March 16, he said: ''I'm not against marriage, not at all, but when you've been with someone for such a long time, I don't think it's going to bring us closer together. I don't think it's going to make us any happier.''
The couple met when Anna, 32, appeared in Enrique's 'Escape' music video back in 2001, and the hunky star admits he knew they would end up together because they got on so well.
He recalled the first time they met: ''She was just the coolest girl in the world to me and we just, we got along.''
However, Enrique's thoughts on marriage may not go down well with Anna as it was reported in October that she was becoming increasingly frustrated with his reluctance to marry her.
A source said at the time: ''[They're] on the rocks. Anna is getting tired of waiting for him to decide if he wants to marry her or not. They've been together for so long, she feels like it's never going to happen. She is ready to move on.''
The novel's author saw a cut of the film and loved each of the changes the movie's director had made.