Request #162

I read a YA book in late 80s/early 90s about an older teenager who agrees to babysit two (?) kids for a single dad over the summer. I think maybe it was set in Canada or the woods or by a lake? At the end of the book the dad declares he’s fallen in love with this teenager and I think he chases her through the woods. I know she ends up a tree with him declaring his (age inappropriate) love for her below. It was a bizarre and, frankly, alarming twist even at the time, but I’d love to find it again