As told to Ann DeGrey.

I always knew my parents had an odd relationship. Dad was a scientist, he was always travelling, carrying out experiments and whatever else he got up to. He was always secretive.

All we knew was he'd pack a suitcase and vanish for weeks, leaving Mum with the house and looking after us. I was 12 when it started feeling normal, while Lily*, my little sister, was only eight.

Mum was always exhausted, she pretty much raised us as a single mum. Dad would call once a week but, aside from that, all Mum knew was what country he was visiting, he just didn't give any details.

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So, as the years went by, we just stopped expecting him to come home; he usually just showed up out of the blue, even surprising Mum. I felt sorry for her and hoped that one day she'd have the guts to leave him and find a man who really wanted to be with her.

I understood Dad was passionate about his work, but having met the kids of other scientists over the years, I realised he'd taken on work overseas when he could have taken on several large projects at home.

So it was a choice he made, to leave his family as often as possible.

Then came his sister, my Aunt Rachel*'s 50th birthday party at the local community hall. Dad told Mum he'd be flying in to attend the celebrations, but Mum wasn't so sure. She knew he was back in Melbourne but, aside from a brief phone call, she had no idea what his movements were. Like I said, it was a very odd relationship.

So, the party was a lot of fun until Dad arrived. He walked in with his arm around a woman we'd never seen. She was a lot younger than Mum, maybe 30, with short red hair and a big smile.

Dad only moved his arm when he came over to me and Lily, giving us a kiss and not bothering to introduce the woman. Mum came over, and the woman went to the drinks table while Dad pulled her aside for a conversation which she had never fully filled me in on.

All I knew then was Mum looked frozen, then turned away from him and went outside.

I grabbed Lily and said we needed to go after Mum. I didn't bother talking to Dad because it looked like he told her the marriage was over. He didn't look at Lily or me, he didn't hug us or explain.

He just took the red-haired woman's hand and walked out the side door.

When Lily and I found Mum, she looked shell shocked. She was with her sister and sister-in-law and when I asked who "that woman" was, she just shook head. My Aunt said, "It's his girlfriend."

Mum told us we'd better go home, and I remember in the car on the way home, she said nothing, aside from telling us Dad won't be coming home again. No explanation, but I guess none was really needed.

The next weeks were difficult, but we eventually got a slight explanation from Mum; Dad met a woman in London months earlier, and he'd decided to be with her. There were no shouting or custody papers. He just stopped existing in our lives. He changed his phone number and the university he sometimes worked for said they had no record of his current project.

Relatives tried calling old colleagues but had no luck. Six birthdays, six Christmases, and not one card. He literally abandoned us. Mum took extra shifts at the hospital where she worked as a nurse and, to make ends meet, she took on some cleaning shifts too.

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Over the years, we all just accepted that he'd left us. After a while, Mum started seeing a lovely man who she was still with. He treats her beautifully and, unlike our father, hasn't disappeared.

We don't talk about Dad much, but we found out via his sister that he moved to London, probably where his partner lives. I keep telling myself that our father chose his own path and that had nothing to do with his wife and daughters.

I try not to think about him too much, but every now and then the thoughts creep in; is he still with his girlfriend, pretending we never happened? Or maybe he disappeared from her life too?

The not-knowing is very uncomfortable, but I've learned to carry it with me.

Mum told us that carrying hurt is better than letting it break you. Lily says one day she might try to find him, just to ask why. I don't think I will. Some doors close so quickly, and cleanly you realise they were never really open in the first place.

*Names have been changed to protect identities.

Feature Image: Getty. (Stock image for illustrative purposes).