Justin Bieber knows what he needs to do to stay faithful to wife Hailey Baldwin! The singer is reportedly FORCING himself to stay away from ex Selena Gomez to ensure his fidelity to his partner.

Perhaps Justin doesn't trust himself around Selena -- after all, lots of people are weak around their first loves -- but her health issues have made it tough. After complications from her kidney transplant which then led to a nervous breakdown, Justin's tendency would be to rush to her side. The desire to go to her, to help her, to nurse her was strong -- hence Justin's numerous public breakdowns right after he and Hailey tied the knot. When he got the news Selena was hospitalized for mental issues, it cause him his own mental issues that he's now been battling.

Justin's been holed up with pal/mentor Pastor Carl Lentz, seeing spiritual guidance and perhaps medical guidance as well. We spotted the singer at the Amen Clinic in LA numerous times before he left town for a self-imposed exile. Reports claim his been dealing with depression and that it's not related to his marriage, but other issues (aka Selena). Seems he's having a hard time letting go and staying away but he knows it's what he needs to do to keep his marriage strong. Question is ... can he do it?