Maybe Adam loves being a dad, some men do, especially as Vanessa had problems bonding with Johnny at first, so I can empathise with him being disappointed that the baby is not his now. I agree that Victoria is not behaving like I would expect most other women to do after finding out their fellas had a baby with another woman after a one-hight stand and even agreed to let them move in!!
Victoria was always feisty and this seems out of character