Do women have more heartache over 50/50 custody than men?

I know a woman who is divorcing her husband. They have a 5yo son. She wants full custody but the law is that the father has equal rights and so it will be week-about custody. He doesn't want to divorce; their relationship has no abuse, addiction, financial stress. It's more about moving apart emotionally, something he says can be worked on, and should be because they both want to be with their child. But she has begun another relationship with someone in another city. So, do you think she will be able to cope with 50/50 custody? Will she regret separating? Is she better off separating even tho it will cost her so much time with her son? My advice to the man is that she seems to be paing a lower value on the family than she does on having a new relationship and so he should let her go. But I'm not the father.