He married elizabeth in 1812 in st peters church liverpool then in 1814 benjamin stanley married elizabeth roberts in st peters church liverpool cant find a death or divorce
Divorces or marriage annulments were rare, difficult to obtain and expensive, so only rich people would try to end a marriage and only in exceptional circumstances.
If an ordinary couple weren't getting on they either put up with it or separated informally and perhaps formed a relationship with someone else, possibly pretending to be a married couple.
If a spouse had left and been unheard of for 7 years they could be declared dead and the other spouse could marry again.
Was Phillip a sailor? He may have died at sea. If his body was washed ashore it would have been buried in the nearest churchyard, probably unidentified.
It was wartime, he may have joined navy or army and died abroad. Men also joined militia regiments for home defence. Militia units could be sent anywhere in Britain or Ireland. Britain was at war with France and America.
Transportation to Australia was a punishment for criminals. Sentences were for a period of years (7 or 14 years were typical) or for life. Most convicts didn't return. A spouse left at home might decide to re-marry.
Registration of deaths didn't begin in England until 1837. Before then you're reliant on church registers, reports of deaths in newspapers and wills.