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She's planning to break up with her boyfriend.
Literal
She [topic-は] boyfriend [with-と] break-up [intend-つもり] is.
~つもり attaches to a plain-form verb to express intention or plan — 'intend to / plan to.' 別れる ('to part, separate, break up') takes と to mark the partner being parted from — Japanese marks reciprocal-action partners with と (compare 結婚する with と for the spouse). ボーイフレンド is the katakana loanword for romantic 'boyfriend'; the equivalent native 彼 is more common in conversational Japanese.