The Christmas Baby's Gift (Harlequin Presents #2365)

Blurb

They had both longed for a child. That was enough for Peta and Liam to decide to get married. Love would never have to enter the equation.

But one year later, Peta is devastated to realize that she's fallen in love with her husband, despite their agreement. There's also still no sign of their much-wanted child, and the heartbreaking reason for that is threatening to tear them apart. Then, just before Christmas, a baby girl is abandoned on their doorstep....