The Marquess Takes A Bride (Mayfair Brides #6)
J.R. Salisbury

Lady Eugenie Hamilton has been told under no uncertain terms she is to accept Trent's advances or face a hastily arranged marriage to the Marquess of Trent. Having known and spent summers riding with Trent, a match with the Marquess wouldn't be so bad.
To make matters worse the Duke of Northshire has asked her father for permission to court her as well. It is a little known fact Northshire is broke and looking to marry someone with a substantial dowry to shore up his debts. And he'll stop at nothing.