I don't think it's any more possible to generalise about men than it is about women. But data from academic studies can indicate common patterns in fathers' behaviour after they split from the mother.
Sadly, some men do behave like this. Most do not. A University of Kent study found the following about paternal involvement:
"Overall, levels of contact were high, with at least 8 out of 10 separated fathers in contact with their child. This is in line with figures from other aggregate sources. Moreover, 6 out of 10 fathers
see their child at least once or twice a week. Of those who had contact, at least 4 out of 10 had their child stay overnight ‘often’ from the age of 5.
We find that whether contact is taking place at all is not affected by fathers’ pre-separation parenting. What does matter for losing or maintaining contact
is the age of the child at the time of separation and the length of time since separation. Loss of contact increases with time since separation and is more likely if the child is younger at the point of
separation.
Looking at how often the non-resident parent sees their child tells a different story, with the involvement of fathers prior to separation making a real difference. Where the father was involved in parenting and had looked after the child by himself, contact tended to be more frequent after
separation. Interestingly, whether the child is a boy or girl affects frequency of contact, even where the level of pre-separation parenting was the same. Contact tends to be more frequent when the child is older at
the point of separation and is a boy. Paternal involvement and looking after the child on his own were both important determinants of the post-separation frequency of overnight stays.
Given contact, time since separation does not have an additional effect on the frequency of overnight stays. This could partly be because overnight stays
are only measured from age 5, and the impact of time since separation is likely to be more acute at younger ages. We also see that boys stay over more frequently than girls.
Overall, we find that, over and above pre-separation parenting, socio-economic characteristics of the parents are clearly associated with post-separation
contact, though somewhat less so for contact frequency than for any contact or overnight stays. This may highlight the importance of resources in, for example, being able to provide a bedroom for
the child, or to find settings and opportunities to meet and spend time with them."
That gives you a bit of a feel for what that study found happened after separation. Individuals' experiences of this will vary considerably. Personally, I have a 50/50 arrangement with my daughters, and we are very close. That's pretty much the norm among the other divorced middle class dads that I mix with (these guys are generally very hands on, involved parents who have a close bond with their kids), but it may not be the norm everywhere - especially if, as @3kids1dad said, you "like to pick the bad ones". Bad boys don't make good long term partners or dads.
What matters for you, is less what is normal, and more what can be done to maintain your son's relationship with his Dad - since there is overwhelming evidence that kids with involved fathers typically have better life chances. That's a case of encouraging that relationship wherever possible.