。
She was satisfied with her life.
Literal
She [topic-は] her own life [with-に] was-satisfied.
満足する takes its target with に, not を — 'satisfied WITH X.' The past progressive 満足していた frames an ongoing state of satisfaction in the past. 生活 covers daily life and lifestyle — career, comforts, relationships, routines — broader than just the abstract 'life,' so being 生活に満足 means a kind of contentment that extends across the texture of one's days.