If it's any help - here are the census returns for them
1871
Heazille Barton, Rewe, Devon
(living in with farmer & family)
Elizabeth Sloman serv. unm. 34 Serv general b. Devon, Burrington
Ware's Buildings, St Thomas, Exeter, Devon
(living with paternal grandparents)
Ellen Sloman G.Dau 6 scholar b.Devon, Ashreigney
27 High St Crediton, Devon
(living with Wm Hopkins & wife - age 55/53 - labourer) no relation
Harriet Sloman nurse child 1 yr b. devon, Crediton
1881
Union Workhouse Crediton
Elizabeth SLOMAN U 41 F Inmate b. Burrington, Devon
Susan SLOMAN 6 F Inmate Crediton, Devon
William SLOMAN 9 M Inmate Crediton, Devon
Ellen still living with paternal Gparents in Exeter
Harriet living in with farmer's family as a servant in Shobrooke Devon
1884 Ellen puts Christopher Sloman shoemaker deceased as her father on her marriage cert.
1891
Tolleys, Crediton
Elizabeth Sloman Head Wid 43 charwoman b.Devon Burrington (age wrong by 10 yrs)
1899 Harriet puts Christopher Sloman shoemaker deceased as her father on her marriage cert. (either not been told she was illegitimate or was lying)
1901
Tolleys, Crediton
Elizabeth Sloman Head Widow 66 charwoman b. Devon Burrington
1911
Same as 1901 but aged 74
I don't think posting this in the Devon section would help as the question isn't about Devon or even the name - it's more about trying to find reasons why someone would be classified as unmarried when they are either a widow or still married (but not with husband and having other children).