Mirabelle admires Joshua's many fine qualities, but he must be ten years older than she is, and a relationship with him would damage her real estate business. And, he has never shown the slightest bit of romantic interest in her.
Joshua has the examples of his father and grandfather to follow, and many years of Dalmatian tradition. He might just have turned forty, but he can't marry until he measures up to the males of his line.
Fortunately for Mirabelle and Joshua, love is no respecter of boundaries. Their hearts conspire against the carefully built reasons that keep them apart. It all comes down to a matter of trust.