The Love Me Now hitmaker, 38, and the Sports Illustrated model, 31, welcomed their daughter Luna into the world 11 months ago, but Chrissy went through a very 'dark time' following the birth, something which John didn't 'see coming'.
Speaking to The Sun, he said
'You don't see it coming. You're not emotionally prepared for someone that's going through a dark time as you're welcoming this new life.
'When you don't understand what's happening, it's a bit challenging to figure it out and you don't know if it's something you've done or some other reason why she's not feeling well.'
'Once you understand what the reasons are then it makes perfect sense and you can adjust accordingly,' he added.
John said while writing the essay Chrissy was 'already doing better', and that they 'want three of four children.'
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