When one partner changes their mind.
So you've been together long enough and you decide that you want to take things further. Perhaps you're thinking of buying a house together, moving to a new country or maybe marriage is the next step of commitment to one another.
Read more: An open letter to all parents (from a non parent)
You've known each other long enough to know what sort of life you plan on living together; what career paths you'll follow, whether you'd prefer to live in a suburb or in the big city, and you've more than likely discussed whether you want kids or not.
"Kids? Hell no!"
When it comes to embarking on your adventure together a lot of couples are saying "no ways" to having kids. With a tough economy, a high crime rate and high population densities it's no wonder so many people are opting not to add children into the mix.
But how often have you changed your mind about something you thought you'd never do or want? And how many times did that change of heart change your life, for better or for worse?
Change is inevitable
I remember when I swore I'd never pick the UK as my working-holiday of choice. The accents, the weather, the thought of not living close to the ocean, these were all strong enough reasons for me to never want to go there.
But circumstances led me there and after living there for two years my visa ran out and I didn't want to leave. I cried all the way home on the plane while I realised I might not ever be able to go back there. I'd even picked up some sort of chavvy South London accent despite how much I detested the sound of it. But I'd move back there in a heartbeat.
I also always wanted to be married by the age of 30 and now that I've almost reached that deadline, I'm nowhere near ready for it. In fact I'm not sure I want that at all any more (but that could change again).
When it comes to life choices, nothing is ever certain. It's worth considering the inevitable changes that happen in life and discussing them with your partner, before you get married.
What do I do if my partner still doesn't want kids?
So what do you do after being with someone who shared your lack of desire to have kids but you feel your needs have changed? It's a tricky situation but there should be no shame in changing your mind.
Your partner deserves to know and you need to start by communicating this openly. Explain to your partner that these feelings have taken you by surprise and that you'd like know if he/she has ever thought about it too.
In the event that your partner is still dead-set on not wanting kids ask yourself these questions:
How important is having kids to me? Has my partner ever shown any signs of wanting to be a parent one day? Is my desire to have kids stronger than my desire to stay with my partner? Am I being impulsive?
Compromise or cancel?
Only you will know whether or not you can truly accept the possibility of not having kids with your partner.
Sadly, many relationships and marriages end when both partners have a difference in desire to have kids. It's a tough truth to consider but it needs to be discussed before taking your relationship to the next level.
Read more: "I can't love you – I don't want kids"
Your partner might have a thousand reasons not to have kids but sacrificing your own happiness to keep your partner happy is a recipe for future marital discord.
Did you change your mind about having kids? Send us your comment to email@example.com.