According to www.familysearch.org, Jenkin Francis Joe wa the son of Lewis Francis Joel and Louisa Elizabeth Dunn, giving their marriage date as 1st April 1877.
Fremont's website cemetries section gives Martha buried at Hillside Cemetery, but the other Joel's areat Greenwood. Also her date of death is shown as 5th May 1879, two years after Lewis marriage to Louisa.
Now this could be simply a transcription error - Jenkin is shown as dying before he was born - I think from the cemetery records the death was actually that of an oder brother Albert.I guess this is more likely than divorce which I assume was much less common in those days.
My interest? Lewis Francis Joel came from the same part of Wales as my ancestors, and althouh I haven't tied him in directly yet, the link must e there!