This is a thoroughly excellent study of the meanings of being unmarried and what it was like and the problems involved in reconstructing this fairly substantial category of the population from the sources.
It's very valuable on the different meanings ascribed to singleness in women and in men and on the relative lack of any discussion of the latter except in terms of 'gay bachelors' resisting marriage.
In terms of my recent work on my paper for the Berks on female relationships at approximately the same period (and looking at many of the same sources, and yes, wasn't Laura Hutton rather remarkable?) I found her chapter on unmarried people (nearly all women) fostering or adopting (formally or informally) had significant resonances with the discussions of female friendship - that on the one hand it could be a valuable emotional substitute for the conventional satisfactions, but on the other there was the danger of emotional over-investment, possessiveness, domineering, etc. Also - some change over time - is seen as more potentially pathological in the post WWII era, which is also when there was shift in attitudes to unmarried mothers, from redemption through keeping the child and maternity to them being neurotic and unfit to mother and therefore the children should be adopted into 'normal' families.
Highly recommended: subtle and nuanced in its analysis, e.g. of the penalties and also the pleasures of being in a family carer role and how contextual those were.