In 1841 Robert appears to be living with wife Elizabeth and family in Stalbridge, Dorset - with Elizabeth listed as not born in County. There appear to be no children born after the start of registration to check his wifes maiden name
There is this possible marriage which ties in well with the husbands residence although the wifes name is Tabitha

Robert Senior
Marriage date 15 May 1815
Spouse Tabitha Jeans
Parish Henstridge Somerset
Marital status - bachelor
Residence Stalbridge
Spouse spinster
Spouse's residence Henstridge
Robert is a widow by 1851 and the GRO Death index has a death of an Abitha below (might a Tabitha??) Could she also have been known as Elizabeth

SENIOR, ABITHA Age 53
GRO Ref: 1843 S Qrter STURMINSTER Vol 08 Page 6