Demi Moore and Ashton Kutcher.

Famous attraction: Demi Moore and Ashton Kutcher had a 15-year age difference. Photo: AP

If you've never had a photo of a penis sent to you on a phone, trust me, it's an arresting experience. The first unprompted missive of this kind is met with confusion, slow recognition, bemusement and ultimately a big fit of giggles. And then it becomes something highly amusing to show your girlfriends in the pub.

I know this because such matters are typical of the weird and wonderful moments in dating a man 12 years younger.

It started with an unexpected Christmas gift. A drunken encounter at a pub on Christmas Eve in 2010 left me waking the next day with a stinking hangover and an unfamiliar arm draped over me. It wasn't Santa, however. This unlikely candidate for my affections was a 23-year-old from Bathurst who hadn't long left uni.

The upshot is that Toyboy, as he came to be known by my friends, has been in my life since then. Reactions have varied from fist pumps and high-fives – "Back of the net, Thomas!" was one comment – to outrage about me wasting my time. "I'm glad you're happy," said one friend. "But what about your withering ovaries?" Another friend casually mentioned she assumed I paid for everything, like a sugar momma (of average means). For the record, I'm not sure I want kids or marriage.

Bills were split equally, and if I have to explain once more that the definition of a cougar is 45-plus, I will actually attack like a wildcat. After that Christmas, Toyboy began visiting regularly. I won't lie about this early period: it was mainly horizontal. It wasn't until about May I noticed how much taller than me he was. His twentysomething gym-honed body and my seen-better-days physique might seem a confronting set-up, but I never felt more uninhibited and fulfilled. A ravenous young bloke in the throes of passion is too busy with far more exciting things to notice a wobbly tummy.

While the photos, which were frequent at this point, were amusing, I was troubled by the etiquette. I am well aware it is something his generation is very adept at, but how does one respond? A polite "thank you", a compliment, admiration of the composition? I never reciprocated, I didn't even try. I'm familiar with my nether regions and I am completely OK with the fact they probably won't photograph well.

As time went on, my friends started to be more bemused about Toyboy. "What do you talk about?" was a common question. There were many generational gaps: it was incomprehensible to him that the world of my teens and early 20s had no internet, whereas it was infuriating to me that anything from music to TV shows had roughly 90 seconds to win his attention or lose it forever.

But, sooner or later, we reached the point where we didn't stop talking. We both had fractured upbringings and many things in common in this respect. He stopped being a plaything and became someone I was very much in love with. A life of hardship and harrowing experiences had not left him damaged or resentful, just smart, funny and good-hearted with a very grounded sense of the realities of life.

He moved to Sydney early last year and began staying at my place most nights. Life beyond the weekend kicked in. Our relationship became less sex and partying, and more about going to the supermarket, eating dinner and the freedom to fart openly while watching rugby league on the TV (mainly him, that one). We became a normal couple.

I knew it was on borrowed time, however. There was always a sense of right people, wrong time and the shadow of an end looming. It finally came to a head at Christmas and now he's off overseas to work, travel and have adventures, much like when I left Britain for Australia nearly a decade ago.

Regardless, there has been something so freeing about a relationship with no future – it's not pointless, it's intensely liberating. No need to worry about marriage, dishwashers, mortgages, kids, money – it's all about the now, enjoying the moment and just being. We leave on good terms, with love and a priceless value on the bounty of this time.

Incidentally, the photos stopped a long time ago and if I mention them now, he blushes. Who isn't embarrassed by the things we did when we were young?