The Earl's Intended Wife — Louise Allen

Hebe Carlton had little idea of her own charm until Major Alex Beresford arrived on the island of Malta. She made no attempt to cast out lures and treated him with warm practicality, showing an insight and ability to read him that few others had managed. His attentions made Hebe blossom, and her stepmother began to entertain hopes of a wedding.

Then a letter arrived for Alex. The proposal of marriage he'd made to another before ever meeting Hebe had been accepted at last. He should be happy... But now Alex could only contemplate marrying one person -- and it wasn't his betrothed!