`Women involved with priests are like the mistresses of married men," says Bishop Pat Buckley, founder of Bethany, the support group for women in relationships with priests. Many priests choose "not to come into the open" about their clandestine affairs. But of the thousand priests who have left the church in Ireland over the last 30 years, Bishop Buckley believes many have done so in order to marry their partners.

Few of the departing priests have been as public about their decision as Father Sean Page, the former curate from St Anne's parish in Sligo, and his partner, Marie Leydon.

"It started out as a pure, genuine friendship," recalls Leydon, a 40-year-old mother of seven from Sligo. "Then in December 1996 my marriage failed. I was a month pregnant when himself walked out. I went to Sean for advice. He was really supportive, and he came to see me in hospital when the baby was born. He even did the christening."

After her husband left, "a year and a half" passed during which Page was a frequent visitor. Gradually she began to notice "something special in Sean's eyes". She admits that, for her too, there was "a spark", as well as friendship, but with a house full of seven children, as well as her mother, there was very little opportunity to do anything much: "It was just normal visiting, with bars and Taytos for the kids. He used to help them with their homework - he was great with the Irish." The youngest, christened Diarmaid but now known as Sean junior, began to call Page "daddy" and the other children followed suit: "They were made to measure," laughs Leydon. "You'd swear all the kids were his, although they aren't." She describes Page as "a super dad": "There's nothing he can't handle, and he can give them spiritual guidance as well." The neighbours accepted Sean calling regularly. "No one pointed the finger."

The first opportunity for "privacy" in terms of their relationship came only recently: "On January 27th we went for a holiday. Up to then there had been no chance for hanky panky. We left Sligo, taking the kids with us, and we became as lovers should be." They are heading back to Sligo this week, now that "the dust has settled". They plan to live as a family and, next January, when Leydon's divorce comes through, they want to marry. "It works in other denominations. I don't see why Catholicism should be any different," says Leydon. "They are missing the basic human rules. Home life and ministry go hand in hand." For Father Sean Page (41), a native of Roscommon, "celibacy is one thing in theory and another in practice. When you're ordained and go out into the world, you miss the camaraderie of the seminary. You get a kick out of making Mass interesting for people, but after the service you go home to an empty house. That's celibacy in action. I feel called to the priesthood but not to celibacy. I want intimate companionship and close family bonds. Sex is only part of the story."

He sees it as "a matter of legalism rather than sinfulness. A sin is intrinsically evil, but a law can be out of date or changed. For example, it was legal to have slaves in St Paul's time, or even in America until fairly recently. But laws change, and with regard to celibacy within the church, it's time to move on. A lot of my colleagues, although they wouldn't admit it publicly, have said to me in private that this celibacy thing has to go. In my view, what I have done is a form of social advancement. I'm ahead of the posse." He cites the case of a priest in Manchester, Frank Meehan, who was forced to leave the priesthood because he wanted to get married: "He was replaced by an Anglican vicar who was married with a family. So you see, it's happening already. These Anglicans who convert are accepted with their families, so why not the rest of us?"

He describes himself as "a recovering alcoholic": "Drink is a great dampener. It cures all ills. Father Jack in Father Ted is an exaggerated version of a sad and sore truth. Priests drink out of pure loneliness." Page was an only child; his father died when he was nine. He joined the priesthood because it was "a secure occupation, a bit like the army". He laughs: "It's not just that. I do have a lot of compassion for people and an interest in communication. I have a flair for the priesthood."

He had felt attracted to various women in the past, but had repressed these feelings because they could not be pursued: "I had to stay within my role as priest. I couldn't go down that road." With Marie there was "a spark", but the turning-point came with the birth of Sean junior: "When I saw him in the hospital, I got the googlies. A lot of men are too macho to admit this, but I'm not. And then when he called me `daddy', the line of demarcation was crossed. I knew then I had fallen in love, not just with an individual, but with a family." He went through difficult months living "a dual existence" as "a trainee dad" and a priest, conscious of being closely observed by his superiors who were wondering "if I'd crossed the professional boundaries": "It all came to a head one day when the bishop called me in and said I'd have to choose between my ministry and Marie and the kids.

"He intimated that if I carried on seeing Marie, people wouldn't want me celebrating Mass. I'd be seen as tainted. He wanted me to shut off and take a retreat. He said this sort of thing happened to many priests and they mature through it and stay in the system. That was not for me. It was the trigger that set the whole going away with Marie idea in motion." He believes that part of his urgency to experience family life is his age: "Forty is a weird age. Half my life is spent. Through fear and circumstances, I haven't had a chance to explore the experience of being a father. I have the chance now and I want to take it. If I had sacrificed Marie and the kids for the love of God, I would have regretted that for the rest of my life. It would have been the lowest of the low to leave that two-year-old baby, who innocently called me daddy, in the lurch."

This week, he and Marie Leydon will return to Sligo to start their new life: "Not to the same exact place. Somewhere in Co Sligo, near but not too near where we were before. And we're sending the kids to a different school. In their last school, which had 600 pupils, they got a bit of hassle. Every school has its share of bullying, and the kids weren't helped by our escapades."

He is bemused by the prospect of becoming an unemployed father of seven: "I have a degree in theology and a degree in philosophy from Rome. These aren't much practical use, so it's back to ground roots. Even if I do say the odd Mass for Bishop Pat Buckley - who makes it possible to believe in a future of married ministry - it won't be a paid occupation. I'll be walking into the dole office like Captain Kirk, going where no person has publicly gone before. I'll be asked for my P45, and I haven't got one. They won't know what to do with me. "A lot of priests have left quietly. Not me," he adds. "Like gays had to 15 years ago, I'm coming out of the closet."