Fredo was a single man [not a family man] with no boundary! to his “sexual excess”

If Fredo “apprenticing as a hotel manager” was “unmanly” Vito would turn over in his grave that Fredo was a pimp, operating brothels

What opportunities were given for Fredo to “being involved with the family business”?
Did anyone bother to mentor Fredo? Did anyone even bother at all with Fredo let alone....even after “having a nervous breakdown”

Sure thing Turnbull “possibly even for failing to prevent Vito from being shot and having a nervous breakdown afterward” is not of Corleone calibre
Was Fredo bodyguard material though How was Fredo licensed to carry a gun?!

Nobody in the family did anything to nurture Fredo the “unmanly” 'different' Corleone unless we count Sonny packing Fredo off to learn the casino business, which made Fredo latch on to Moe Greene “we are good friends” even after Moe slapped Fredo around in public including Fredo's angry outburst at Michael and later Fredo latched on Roth / Ola because Fredo was treated as the family pariah, at every turn

Poor Fredo copped it from everyone – Vito, Carmela, Sonny, Michael, Greene, Deanna