Complex sentence: She began a partnership/marriage with John James Pleasants circa 1848, although no records exist of it, their marriage was probably conducted by their friend Captain Gardner, Phoebe's husband, on his boat.
Split into simpler sentences: She began a partnership/marriage with John James Pleasants circa 1848. Although no records exist of it, their marriage was probably conducted by their friend Captain Gardner, Phoebe's husband, on his boat.