Let me rephrase that: at the mixed seating weddings I’ve been to vs the seperate seating weddings I’ve been to, there have been approximately an equal number of men on the womans side.
I’m not sure what aveiros would occur when you are surrounded by 400 people. But you may meet your bashert!
On Tu B’av women used to dance in the field and the men would pick them. So if you go to a wedding on Tu B’av there should be no reason to have the singles seperated right?
When I go to a simcha, I like to sit with my husband. We work all day and if we spend our precious evenings or sundays at a simcha, I want it to be with him. If we know the affair is seperate seating, often one of us stays home with the kids.