Whenever she argues with him, she always ends up compromising.
Literal
She [topic-は] he [with-と] argue [whenever-と] always compromises.
The conditional ~と is used here for habitual, inevitable consequences: 'whenever X happens, Y always happens.' Distinct from ~たら and ~ば, ~と has the strongest sense of automatic or routine cause-and-effect. The いつも reinforces the habitual reading.