why is there no 'til' before the 'at' in this sentence?
there was one after the 'mig' in this sentence: 'Min lærer har tvunget mig til at svømme'
A little late, but!
Like in English, you "force someone to doing something", but you "allow someone doing something". So at tvinge requires to use til but tillade doesn't.
It should allow 'she has never let me swim at night'. In BrE at least, it means exactly the same thing.