Poppy Day by Anne Murray
If you persevere with the story line you will enjoy it. Jess has left home because she is unhappy with her father and his new wife, and they are marrying her off to someone that she dislikes. She goes to live with her Mother's sister who has secrets of her own which come to the surface when Jess goes back in to her life.
However, she takes her in and Jess settles down with the rest of the family who are Sis, the youngest, Polly, Bert and baby Ronnie and gets a job. Things go well until she falls in love with a family friend who is already married and whose wife is expecting their first child. They meet secretly but things come to a head when he tells his wife he is leaving her. Auntie Olive puts Jess out and she finds rooms with an elderly lady but she is expecting Ned's child. Ned who has a daughter of his own now agrees to divorce his wife Mary eventually. His family is against Jess and when she looses the baby it takes the urgency away and life rolls on.
War is declared and Ned goes off to fight but spends his leave with Jess. Eventually, he is wounded and goes to convalesce at his own home. His family are against Jess and won't let her see him..It is quite an interesting book and has several incidents not all have been mentioned which slowly unfold throughout.