Not What it Seems by Pamela Fudge

Evie was divorced with three young children and Owen was widowed with two of his own when they were introduced by friends. There was no attraction between them, but they came to realise that as working single parents they could help each other with the very real day-to-day problems of childcare.

As a practical arrangement, setting up house together worked beautifully, and now that the last child has flown the nest it is time to ditch their unconventional setup and lead their own lives, just as they had always planned. But cutting such strong ties is never going to be easy, and it’s going to be a long and difficult road if they are to separate their lives and home for good.