It's absolutely not listening. How do you think a huge company like facebook could get away with that, without a single one of their thousands of employees going rogue and selling the info on it to the press?
Humans are really, really good at picking up on co-incidences. That's why we often see things that aren't there, or read into things more than we should (the classic 'seeing a face drawn in the clouds' being one example).
Facebook ads are targeted in a lot of different ways, including by demographic (for example, young men living in city = likely to buy a suit), by the groups you're in (e.g. in a mum and baby group = likely to buy a pram), by messages (e.g. mention wedding to a friend = likely to click on wedding dress adverts), and by your browsing history depending on your settings and if you're logged in (e.g. google breast feeding = adverts for breast pump).
They also advertise random stuff as their targeting isn't always right- most of which you turn a blind eye to and don't even notice. If, however, you've been thinking about it, and then it happens to be on your page, you are sure to notice it and perhaps then think it's a huge conspiracy. It's really not.