Nick Jonas was ''jealous'' in the early stages of his relationship.

The former Jonas Brothers singer - who has been dating Olivia Culpo for 18 months - admits that it took time for the couple to build up the trust between them.

He told the New York Post's Alexa Magazine: ''I think earlier on in my relationship, there were times where I would get jealous.

''I think with time and trust built up, a lot of that went away. We have a really strong relationship now. It takes a second until you feel really locked in with someone.''

Meanwhile, the 22-year-old singer also opened up about his ''healthy'' sex life.

He revealed: ''As far as the sexuality goes, I think that just happened for me over time, I think sex is part of a healthy life.

''So I have tried to be, in my transition into adulthood, as honest with myself as possible with sex and sexuality and what it means to me so I can try to be as healthful as I can.''

Nick - who wore a purity ring as a teenager - admitted that he doesn't regret the decision.

He said: ''I don't regret [wearing a purity ring]. I think that it was an important part of my childhood.

''As I grew up, I sort of figured out what was important to me, my own belief system, which we all grow up, we all live life and find out what's important to us. I am now comfortable with who I am and what I believe in.''