、。。
Love is like measles — everyone has to catch it once.
Literal
Romantic-love [topic-は], measles [like-のような] thing [copula-だ]. Everyone once [topic-は] must-catch.
A two-clause aphorism with a vivid simile. ~のようなもの ('a thing like ~') is the standard nominal-simile pattern. The verb かかる on the second clause is the same one used for catching diseases: 病気にかかる. ~なければならない is the obligation construction ('must / have to'). Note the は after 一度 — contrastive, marking 'at least once' (with the implication 'though hopefully not more').