The science of Love or Love-making, as from the stem phil-, meaning love/enthusiasm (bibliophile = book-lover, pedophile = child-lover), and the suffix -ology, referring to a science (physchology and Biology for example). This is to be differentiated from a specific sort of philology as Romance Philology, the study of Latin (literally "The Science of Loving things Roman").
-Man, I gave her a 3-hour lecture in philology last night, if you know what I mean.
-Oh, sweet. I knew she had it bad for you.