The Rancher's Mail-Order Bride by Mindy Neff

Wyatt Malone had been ambushed! The little boy staring earnestly at him thought Wyatt was his new dad--and the boy's pregnant mommy claimed to be his bride-to-be. The old matchmakers had gone too far this time and now it was up to Wyatt to tell Hanna Richmond and her adorable son that they'd been had by four well-meaning, old cowpokes. Except that when Hannah looked at him like he was the best thing since sliced bread and made him feel like a complete man, Wyatt began to think that maybe the old fellas were right--and that could be dangerous for the whole town!