While there are virtually no examples of men blithely standing by as their girlfriends and wives broadcast their lesbian exploits (though Hollywood's PR machine waits in hope for Anne Heche's return to the hetero highway), Eadie is only one of many women who accept that sexuality is neither an absolute, nor ultimately the most important thing in a relationship.
Fabric designer Celia Birtwell's marriage to the Sixties fashion designer Ossie Clark, for example, famously allowed for Clark's sexual ambivalence and the relationship was a happy one for many years. Even after the couple parted and Clark openly dated gay men, he wrote in his diaries about the strong affection he still held for his ex-wife and the mother of his two sons.
Jon Moss' affair with Boy George in the Eighties has done nothing to disrupt his heterosexual relationship with the mother of his child over the last few years (although George's plaintive cry in `Do You Really Want to Hurt Me?', directed at Jon after a lover's tiff, must be wearing a bit thin by now ).
More recently supermodel Iman has felt confident enough to marry David Bowie, a man who seemed to spend the Seventies in face paint, risible body suits and a variety of bisexual clinches.
"Despite a certain amount of ignorance, there's an understanding now that most of us have multiple sexualities," says Dr Mick Cooper, senior lecturer in counselling at Brighton University. "There are very few people who are 100 per cent heterosexual or homosexual - most of us lie on a contiuum between the two extremes. So it doesn't mean that someone who has a lot of relationships with men and then has relationships with women is living a lie - they're just expressing a different part of themselves. Unfortunately we're still living in a society which thinks people should be consistent."
Hence those persistent rumours - since denied - that Portillo and fellow Cabinet member Peter Lilley had more than politics on their mind during their time in government. While Carolyn Eadie seems unmoved by the whisperings (the Portillos and Lilleys frequently socialise together), the idea that you-are what-you-were pigeon-holes sex as the driving force in a relationship. Yet most couples who have been together for more than five years will know that the days of working enthusiastically through the Karma Sutra and hanging from the chandeliers have taken a back seat to other, more durable qualities - companionship, compatibility, the hard-won truces over who has control of the TV changer.
This was the case for Samantha Williams, 33, who after four years with her boyfriend, realised he was struggling with gay feelings. Happy in her relationship, she felt confident enough to let him experiment with other men. "It took ages for him to find the courage to make a move and we talked quite openly about it," she says. "Our sex was always lovely and finding out that he was capable of a gay relationship really didn't make any difference to us. We were in love and he was a wonderful boyfriend to me. People assume that sex must be the only thing that matters in a relationship, but it doesn't have to be. People make compromises in every other aspect of their lives, so why not sex?"
It boils down to a simple question of priorities. For some it's material comforts. For others it's great sex. For others it's a deep friendship. For gay fashion designer Julian Simpson, 35, it happened to be a family. "Julian was desperate to have a `normal' love life - to have a wife and kids," says Lizzie Forrester, 28, with whom Julian had a six- month affair. "He was very uncomfortable about his homosexuality because his parents were strictly Catholic, and I know he felt relief as much as anything when he met me and realised he could actually have strong feelings for a woman, even if he still felt attracted to men."
Like Portillo and Eadie (or "Squirrel" and "Splodge" as they reputedly call each other) Lizzie knew all about Julian's sexual past and felt comfortable with it. It strengthened their relationship, because there was no need for Julian to hide an important part of himself from her.
"It was only when I met my husband that our relationship faltered," says Lizzie.
"He was very upset when we broke up and I don't think he's been with a woman since. But we were definitely in love for a while back then. If I hadn't met someone else, I daresay we could have happily ended up together."