Not very canon, but never mind...
Overheard – Bogwitch
(Spike/Buffy, Season 6)
Willow learnt much from reading on the sofa, but not from her books.
She’d had to look, the sounds from the front garden, muffled voices and low sighs, could be demons prowling - or burglars, you had to watch for those.
Spike buckles his belt on the porch, unaware that the window is open and Willow can hear the clink of the metal as it locks in place. Then she catches the longing look Buffy gives him as he swaggers down the path to the road, and they're given away.
It’s not right, but she’ll keep their secret for now.