I'd be inclined to agree apart from the fact that I've had a couple of my favourite spots for a night stroll/biking trailheads turned into porntastic dogging spots where you feel particularly unwelcome, embarrassed and mildly disgusted by being there. Take, for example, my local beach - used by me and others for dog walking, horse riding, sunbathing and kitesurfing. Apparently now its a hot dogging spot and the local doggers are out peering through bushes and having a ham shank over you and your missus when you're just there to sit in the sun or have a walk at night near the sea. Again at one of my local riding spots I often came back to my car and had to get changed and pack the car while there are bunches of people stood around fiddling in (and over) the car parked NEXT to my car. I've actually had to chase one chap at the beach, who repeatedly came back and stood pleasuring himself in the tall grass while my missus lay on the sand.
I'm all for personal freedoms within reason, but when it's making the rest of the public want to avoid places I think it's a step too far.
In this case I think I'd probably not say anything, but I'd not avoid her just because she put me in that situation.