Short answer: No — it starts that way, but becomes more.
From the provided Recapy summary, Allie takes Dean for "just once" while she's nursing a broken heart (so the hookup is initially a rebound/one-night stand), but Dean doesn't let it end there. He pursues her, and as life-changing events unfold he begins to consider something deeper than casual sex — the relationship develops into genuine romantic territory.
Sources: Recapy context pack (provider metadata) for The Score by Elle Kennedy (2016).
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