Has she said she feels she has lost her "self" or is this your surmising? Just wondering before I get into it. Not that either is right or wrong it will just reflect which books I recommend.
Are your kids young? That is a hard time. It's just such a busy time. People always say "find time to do thus and such" but that is the main problem. There is no time! Not till the kids grow up and leave home. Then it's empty nest that hits and hurts.