My partner and I had been together for eight years when we changed the nature of our relationship. She and I had tried an open relationship before; it led to recriminations, arguments and eventually a break-up. But this time was different: we dated people together, inviting them back to our bed. Being rejected, flirted with, turned on, let down, tied up: we were experiencing every wonderful-awful aspect of dating together.

I’ve always struggled with the idea of monogamy. And we were both sluts; now we had found a way to be ethical ones. The experiment has been aided by the discovery that we are both bisexual. Neither of us had slept with a person of the same sex before, despite being curious.

The reactions of our friends have ranged from predictions of a second break-up to a lascivious interest in the mechanics of threesomes. A disturbing assumption is that I must be strong-arming my partner into the arrangement: female desire could surely not accommodate such a set-up. This is patently false, we find ourselves explaining. And yes, we still enjoy sex with each other.

My life in sex: ‘Monthly isn’t enough for my libido’ Read more

We joke that we are a bisexual power couple, but there is always a worry in the back of my mind. Surely I can’t be so lucky as to have the love of a wonderful relationship, with the sexual excitement of a rampantly single twentysomething? There will be challenges ahead, especially when we begin to think about having children. But I believe our mutual trust – and passion – will ensure that however we navigate them, we will do so in the most fun way possible.

• Each week a reader tells us about their sex life. Want to share yours? Email sex@theguardian.com