The well-documented relationship between Britain’s “first gay dads” has officially come to an end — as one of the men is now “in love” and dating his daughter’s ex-boyfriend, a report said.

Tony and Barrie Drewitt-Barlow — who were England’s first same-sex couple to be named on a birth certificate as parents — have parted ways and Barrie opened up about their new unconventional living arrangement to The Sun on Saturday.

“I’ve fallen in love with Scott and he has done the same,” said Barrie, 50, referring to the ex of his 19-year-old daughter, Saffron, who is openly bisexual.

“I feel stupid at my age to have these feelings about someone other than Tony and half my age. But when you know something is right, it’s right. We have not made definite plans but I would like to marry Scott.”

Scott, 25, and Barrie are continuing to live in the family’s $7.5 million Florida mansion, along with Tony and Saffron and the rest of the family.

Barrie told the paper that his estranged husband and Saffron are accepting of the relationship.

“I’m not having a midlife crisis — if I was having one, I’d buy myself a Porsche 911,” Barrie said.

“This is the real deal. But not everyone will get it, as our living arrangements are unorthodox — I feel like I’m living in a commune, we are all still living together.”

Barrie and Tony in 1999 welcomed twins born to a surrogate and declared themselves “Britain’s first gay dads,” The Sun said.

The couple became civil partners in 2006 and married in 2014 once it became legal to do so in the UK, the report said. They have five children.

Barrie said that while Tony is his “true love,” they grew romantically distant in recent years, with the two sleeping in separate bedrooms.

That, together with Tony’s deteriorating health following a 2006 cancer diagnosis, led them to drift “into a platonic relationship.”