The actor says that challenges – including his wife's stint in rehab – has made their marriage stronger
Credit: Gregory Pace/Rex USA

Antonio Banderas and Melanie Griffith are a rarity in Hollywood – a couple married for 15 years and still going strong despite divorce rumors and stints in rehab. So, what’s their secret?

“There is one virtue that is very underrated and that’s passion,” Banderas told PEOPLE at the New York launch of his fragrance, The Secret. “If you lose your passion, all these other virtues that are way more important, they just all fall.”

The actor, 49, who also displayed his first photography exhibition “Secrets on Black” with pieces auctioned via Charity Buzz to raise money for Broadway Cares/Equity Fights AIDS, says that hard times can make a union stronger.

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“We have been in crisis sometimes and we knew that if just waited to cross that tunnel that we were just in, at the end we were going to be stronger,” he said. “We believed, very much, in each other and we’ve been battling with everything that happens in our lives because at the end we knew there was a reward. And the reward in my case was her.”

Last August, Griffith, 52, headed to drug rehab after relapsing for the first time in 10 years. But it wasn’t just Griffith’s fight with substance abuse that invited tension into their relationship. Banderas says the couple has heard from their fair share of not-so-well-wishers since they first tied the knot.

“We both were coming from two different relationships that were failures and you learn a lot from that,” he says. “[People] made bets that we weren’t going to last more than six months.”

Joked the actor: “I should have taken them; I would have made some money!”