Friends of singer Selena Gomez are said to be worried she may fall back into "old bad habits" and start dating Justin Bieber again since her good friend Taylor Swift has found love with Calvin Harris.

The "Heart wants what it wants" hitmaker is feeling left out since her friend started dating Calvin Harris and an insider claims she is considering reuniting with on/off boyfriend Bieber, reports femalefirst.co.uk.

"Taylor is totally consumed with Calvin right now and barely has time for Selena. Taylor was always on Selena about staying busy and staying away from Justin.

"Without Taylor's influence Selena is more vulnerable to falling into some old bad habits. She doesn't have a guy right now either and she hates being alone so it's all adding up to a bad combination," a source said.