Hang on, he can work wherever he wants whenever he wants but he hasn’t chosen to do that yet? Sounds to me like he’s spent the whole pregnancy making her empty promises! She’s living in La La Land.
They should have got some experience of living together before even trying for a baby, let alone before one actually arrives. Having someone visit overnight for a nice meal and some sex a couple of times a week is a very different picture to when you’re actually living together as a family unit. He might be good to her and the kids on a part-time basis, but chuck him in at the deep end as a full-time dad with a full-time job and a full-time responsibility to pay the bills for a family of 5 when he’s used to his tradie income being mostly disposable, and they’re both in for a big shock.
I give it a generous 3 months before the novelty wears off and they’ve decided to go on a break. On, off, on, off, on, off until the next baby to try and fix the broken relationship, on, off, on, off, and then another bloke comes along and the cycle repeats. The lady in the comments that knows her has it sussed.