Les Liaisons Dangereuses

These guys have been doing a slow circular dance since breakfast time.
I guess the small one will end up as dinner for the big one, once he has fulfilled his destiny. Women! You can't trust them! (Better in large.)
(Post script: They were still there Monday night, but come Tuesday morning the window is empty. Does that mean
1 they've eloped?
2 she's eaten him and gone off to lay eggs?
3 a bird has interrupted the nuptials for a tasty snack?
Answers please!)