Pop star Justin Bieber and singer Selena Gomez plan to get married one day because they think their connection is unbreakable.

Bieber, 20, has had an on-off romance with Gomez, 21, since 2010, but wants to show her he is serious about being with her forever, reports contactmusic.com.

A source told Life & Style magazine: "Justin has told Selena he will marry her. They're young, but feel like they have a deep connection that no one can break."

The couple have already started "playing house" at Gomez's house, but her friends are still worried about her.

"She's not in a stable place right now where she's making the best decisions. She told him that she will marry him once he proves to her that he's serious and stops cheating on her. He's really trying to change for her and wants to be with her forever."

"Everyone close to her thinks she's crazy and can't believe she took him back again,` said the source.