By all accounts, Harriet (aka Henrietta, or Henriette) Smithson was a friendly, attractive, and available young woman, making her a likely candidate for the admiration of Belioz, or any young man. But it was her portrayal of Ophelia in the 1827 performance of Hamlet that won the heart of Berlioz, and, along with her successive performances as other Shakespearean tragic heroines, made her famous among the French- regardless of language barriers that compromised understanding of the plays.
Further Reading:
Harriet Smithson Berlioz
The Smithson Obsession