Alright. I'll bite.

Why is this a gendered issue? Nice people are single, while horrible people have plenty of relationships. There's many facets to how people of both genders choose partners, "niceness" is just one of them.

Is the point that men who whine about being single are attacked while women are allowed to bemoan their status?

If that's the point he's making, its mostly because he is saying he "deserves" to be in a better situation then Henry. I rarely see women say they deserve more men then another women. If anything, I see them discuss deserving a good caring partner. See the difference? "Why do other people have what I don't have" comes off very differently then "this is what I want". One is about jealousy, the other is about personal goals.

TLDR: Of course he is allowed to whine, but just like most self-pitying diatribes online (male or female) they tend to not be well received.

Bonus Note: Also comparing normal dating to abusive partners is beyond ignorant but I don't have time to write a well sourced piece on that right now. Maybe I'll add it later.