@ItalianHat
It's not just the issue of their relationship, but the fact that he seems to have a fear of commitment to anything or to anyone and is getting depressed about how his 'life has turned out' (his words)
I know you're his mother, but you may not like what I've got to say. I spent 3 years with a man like this in my early 30s. At first he was serious about a family & settling down etc. But he started havering & making excuses. Having hooked me in - I wasn't that bothered about having children before my relationship with him, but I really wanted to have children with him.
Anyway with the havering and the to-ing and fro-ing, it took around another 2 years to realise that in the end it wasn't going to work.
Not once would he take responsibility for this. He manouevred and havered so that in the end, I had to finish it. I think he didn't want to look like the bad guy. I was 38 by that point and I could see my fertility slip away (indeed, it had). I really feel that he "stole" my best years by vbeing a Peter Pan.
It still gives me the rage when I see newspaper articles or the like telling women to get their fertility sorted out. In my experience., it's usually the man who is the delayer, who doesn't want to take responsibility for participaring in an open & honest relationship ie grow up.
So - my advice to you as his mother is to tell him that if he really thinks a family with this woman is not for him after 5 years he OWES her - a lot. He owes her the respect to get out of the relationship as soon as possible, and as kindly as possible, to give her the chance to recover & see if there's a better man about who is responsible & grown up.
He owes her to make it easy & he owes her to make any financial arrangements generous towards her. If she wants a family, he's done a fair bit towards scuppering her chances.
"Depression" is not an excuse - he's been less than open or respectful to the one person in the world to whom he has a deep responsibility.
So if you can't say any of that to him, advise him to leave her, and explain to her why. Make it a clear clean cut, and don't faff about pretending he's having a crisis etc. Tell him to have some respect for the woman who trusts him.
Completely agree with you about women being blamed when it's non committal men who are mainly the issue.
However like you said, they wouldn't be able to steal women's fertile years if we didnt let them. This modern day living where women are primed to give all the benefits of marriage to a man (living together, domestic labour, sex, emotional support etc.) without their commitment and expected on top of all this not bring up marriage/kids for fear of 'pressurising' or 'scaring him away' is utterly ridiculous. We need to be pushing back against the selfish indulgent Peter Pan role men are afforded in this sexist society, speak up for our expectations/desires as women, and kick such men to the kerb much earlier.