Another Kind of Summer — Tressie Lockwood

Summer has known since she was seventeen years old that she can't have kids, but Ian doesn't care about that. He loves her and wants her to be his wife. Although she loves him with all her heart, Summer refuses to ruin Ian's life. She leaves him to set him free, and he moves out of town believing their relationship has no hope. Four years later, Ian is back, and this time he won't give up so easily. When Ian turns up with a newborn son, Summer is even more convinced that she is not the woman for him. Now, she must convince Ian that she's just not the mommy type.