I have a feeling that this is all related to the entry of women into the workplace. Don't get me wrong; patriarchy is oppression and it has to go- but I think there were a lot of jobs being done by women which are now being done by nobody, and among those are the jobs of maintaining social cohesion and networking and so forth, which are a lot easier to do if you and your friends are somewhere other than at work at th…
If women worked and men all stayed home, did chores and social networking we would not be lonely again.
I don't think it has much to do with gender so much as "we have less free time." It just shows up as women working, but I don't think women working is the cause, merely a symptom.