I believe it was her husband who was the sot.
He drank after she had the affair with the younger, married man.
How that conduct was logical beats me.
They were all a pile of drunks from all I have read. Rand had an affair with Nathaniel (I forget his surname) and her husband drank even more but didn't stop it.
The Fountainhead is the only semi-readable book Rand ever wrote. Atlas Shrugged makes a great doorstop.