Trees object of obsession is bit, obviously. On account of he's a little crazy. But it's still a perfectly straight thing to do lots of crazy old fellows out there chasing poon like a dog trying to chase a squirrel gone up a tree.
Your object of obsession is treefingers. Said crazy old boy.
I guess the difference is that he's obsessed with a woman he will never get, and deep down he knows it. He's acting out on account of finding that fact hard to accept I reckon. Also cuz he's a little crazy. You on the other hand. Your object of obsession is a crazy old gorilla nest building madchad who lives in a trailer and can't get his driver's license, on account of he's kinda retarded and crazy so they don't want him drivin'.
The other difference is he knows he's a crazy old man who doesn't got a snowballs chance in hell of scoring bit while you're in denial about being attracted to him and him being the object of your obsession.
It's real cut and dry from where I'm sitting frankly