。
It's not that she always travels to France when summer comes.
Literal
She [topic-は] summer [becomes-と] always France [to-へ] travel-do [is-not-the-case-わけではない].
~わけではない is the go-to pattern for partial negation in Japanese: 'it's not (necessarily) that ~.' Different from a flat negation: it pushes back against an inference rather than the bare statement, often softening or qualifying. The conditional ~と attached to 夏になる expresses an automatic 'whenever it becomes summer' frame, and いつも ('always') sets up the thing being denied. The whole shape — frame + いつも + ~わけではない — is one of Japanese's clean ways to say 'usually does, but not invariably.'