When they first met and fell in love, everything was perfect. He was the most attentive, kind dude and she was completely head over heels for him. When they accidentally got pregnant, the boyfriend became even more attentive and caring. He started working harder and buying baby things, giving her extra attention and love, they talked about all the Kodak moments and how excited they are. They plan everything and make sure the child rearing will be 50/50. The world is pink and they are the most in love they’ve ever been.
Then the baby arrives. He initially does 50% but months go by and she realizes she’s started doing the lion share of it. Their relationship starts to crumble as the day to day stress of having a child puts a strain on their relationship. After nearly two years, they are miserable and resentful of eachother.
Then they remember what it was like before. When she was pregnant. And they desperately want to go back to that. So instead of working on their relationship with a professional to get it back where it used to be, they assume it’s because of the baby. They think that being pregnant will bring them bliss and make them happy again. Initially when she gets pregnant, they are overjoyed. But the fog lifts much faster this time around. As the pregnancy progresses, they realize they are still miserable and are now stuck in an even shittier situation.
Obviously this isn’t for every case, but it seemed like a very likely thought process