The Daughter He Wanted (Harlequin Super Romance Book 1971)

The Daddy Surprise 

Since the loss of his wife, Alex Ryan has been living a half-life. But with one phone call, Alex discovers he's the biological father of a four-year-old girl…and everything changes. 

Single mom Paige Kenner preferred to have a family without the man. Now suddenly there's Alex, who desperately wants to be a father to her little girl. A gorgeous, kind and committed father. Letting a stranger into their lives is far too dangerous—especially if his presence stirs a part of Paige that she longs to forget…