I don't believe it was addressed in this piece, but the general desire of women for men the same age or older is also relevant. I've read elsewhere that the supply and demand dynamics on Tinder and other dating sites become so unbalanced for moderately successful men (even nerdy types) in their early-30s that there are dozens of women trying to "catch" them. This makes it even less likely that they settle down just when their options are increasing. And attractive, smart, caring women who want to get married arrive at age 30 and find that the 40:60 ratio from college has turned into 10:90 when an "eligible" man means 30+, still single, educated, high salary, tall, etc.

resulting suspension was transferred onto sterile 0,2 μm nitrocellulose filters (Advantec) that were placed over 10% TSB agar media

2 ml of mating suspension was transferred to a sterile 0.22-μm Cyclopore membrane (Whatman) by vacuum filtration (<0.4 mbar)