。
She married a classmate.
Literal
She [topic-は] classmate [with-と] married.
結婚する ('marry, get married') is a reciprocal verb that takes と for the partner — 'marry with X.' This is one of those verbs where the English direct-object framing ('marry someone') doesn't carry over: in Japanese you grammatically marry *with* someone, not *to* them. The distinction reveals a basic structural fact — Japanese encodes joint actions (会う, 結婚する, 話す, 別れる, 喧嘩する) as inherently reciprocal, with both parties marked as joint participants rather than as actor and target.