The Weary Heart by Mary Lancaster

Pride versus passion
Sir Marcus Dain lives for adventure. Most other things, including his large estates and his inevitable marriage, he considers wearily to be matters of duty rather than pleasure. Until he encounters fearless, intriguing governess, Miss Helen Milsom, at the Hart Inn.
Sparks fly in terms of both temper and desire, but something in this quite unsuitable woman touches his cynical heart. Then old promises and devious, matchmaking mamas get in the way.
Helen, having lost her chance of marriage ten years ago, is resigned to spinsterhood. Holding onto pride, which has seen her through many difficulties, she fights her inappropriate attraction, even when she is falsely accused and loses her position, and Sir Marcus offers her only safety.
Misunderstandings and the villainous behaviour of Helen’s one-time betrothed, combine to part them, but Marcus will not give up and sets out to remove all the obstacles to their happy-ever-after.