I could see how it could place a husband in the occasion of sin if he had a majority of female friends, but it is an occasion of sin for a husband to have close female friends (in addition to his wife, too, of course)? Would this be to give scandal, if he associates with them with or without the presence of his wife?
The closest I've seen a Catholic author address this is T. G. Wayne's Morals and Marriage: The Catholic Background to Sex (nihil obstat & imprimitur 1936):The pleasure normally taken in the company and conversation of the opposite sex is clearly not meant to be restricted to marriage.
I suppose this question falls under the broader question: "What should a husband's relation to other women be?" Should he charitably avoid them, preferring to associate with males only?
I'm also reminded of Padre Pio saying he never knew the face of a single female of his congregation. Is this the approach Catholic husbands should take with women they're not married to?
I think that every person's situation is different, but caution must always be advised...
That being said, I don't think that a married man should have a close female friend that his wife does not know about, or with whom he spends time alone with. This easily becomes a near occasion of sin even for people who are most holy and devout.
I can offer first hand experience...
Since I was a girl of 18, I have had trouble with married men looking up to me more than their wives, and it has really caused A LOT of trouble!
I never did anything wrong, and only spoke to some of these men as merely a cordial greeting or conversation at Church, dinner, or something of similar sort... Yet, the jealousy of of a wife is not to be underestimated.
I have had a number of even traditional Catholic women despise me just because of the fact that their husbands looked up to me or spoke with me at all. Some of them even went so far as calling my parents, asking them to tell me never to see or talk to their families ever again (which is weird because my family is N.O. and never met or heard of these people...)
So, basically, for the sake of the sanity of your family, and everyone in your society or at your chapel...
Please, all married men, think twice before being close friends with another woman besides your wife without her absolute consent and approval... I would not want anyone to have to go through some of the same things that I had to bear, through no fault of my own, except perhaps being innocent and naive...