。
She knew that John loved her.
Literal
She [topic-は] John [subject-が] is-loving [thing-of-の] [object-を] knew.
The outer 知っていた ('knew, was aware of') is past, while the embedded 愛している ('is in love, is loving') stays in the present continuous — together they say her past awareness was of an ongoing love. Notice the deliberate absence of the benefactive ~てくれる: without it, the love sounds neutrally observed rather than personally received — closer to 'she was aware of John's love' than 'she knew John loved her specifically.' Subtle but real shift in emotional framing, made possible by Japan's rich benefactive system.