The ‘McFly’ drummer, 31, and Izzy have two children: Lola, 20 months, and Kit, two months.
“Izzy so desperately wanted to be a mother and so as soon as we realised there was a problem, it took over her life,” Harry told The Sun’s Fabulous magazine.
“The dynamic changed because all the focus was on getting pregnant and in a way I lost her a little bit. I lost that smiley, confident, beautiful wife.”
The couple first started trying for a baby after their wedding in 2012, but Izzy found out she had polycystic ovary syndrome, which led to problems conceiving.
In 2014, they had a successful round of IVF, but Izzy suffered a miscarriage after seven weeks.
“Our wedding had been the happiest day of our lives – cut to a year later and she’s [Izzy] in absolute despair,” added Harry.
“I remember after two years thinking: ‘God, we haven’t even had a kid and already I’m sick of this.’ It was constant but I felt I couldn’t get frustrated at her.”
They welcomed their first daughter, Lola, via IVF, and conceived their second child naturally.
When announcing they were expecting their second child in April 2017, Izzy, who has written a book about her IVF journey, shared her story with the aim of giving hope to others who may be struggle to conceive.
“After having IVF to conceive Lola people used to say to me you’ll probably fall pregnant naturally next time,” the mum wrote on Instagram.
“I wondered how it would ever be that simple after all the difficulties we have previously faced. I never believed we would be lucky enough, but whilst writing ‘Dare to Dream’ this little miracle happened.
“I want to give others hope that amazing things can happen.”