100% this.
Problem is @Youdontseehow most men just can't stand the thought of women having something to themselves. Something they enjoy. Something they BENEFIT from. Even my DH had a whinge once as to how it was soooo unfair that the Womens Institute didn't allow men, and it's sooooo sexist. Like as if he would go anyway, even if he WAS allowed. I said 'create the MENS INSTITUTE then if you're that bothered!' He was just like 
And a woman I knew once had her own little womens group at her house every couple of weeks for chat and coffees and teas, and one of the womens husbands asked his wife to ask the host if he could come. She said no. It's just for women. A private meet up group for women. He said 'not fair' too! Again, it was suggested to him that he creates a mens meet up group. He also frowned, and pouted like a toddler - but did fuck-all about it.
Some men don't want to join in with women really, they just want to stop women having private, safe, secure spaces where they can discuss womens issues/life's issues in general. And they poke their nose in, and stick their oar in to try and derail it. As you say, there are many things that women just can't discuss with men. Or don't WANT to discuss. And there are many MANY issues women face that men don't have a fucking clue about!
As I said, I find it very odd that men want to come here. Genuinely, really weird.
And I don't care if SOME women on here 'don't want to be on a women only forum.' Some women do. And nobody has any right to tell them that they have no right to feel this way! No matter how much they would like to. 