The Trouble With Playboys — Margaret Tanner

When a wealthy Englishman, Paul Ashfield travels to Australia in search of the birth mother he thinks deserted him, he never expects to meet and fall in love with Daphne Clarke. Upon meeting her parents, Paul is horrified by the possibility that they may have the same mother. He beats a hasty retreat, leaving Daphne heartbroken. Amidst the turmoil of WW2 they meet again in Singapore, just before the Japanese pour into Malaya, and in the chaotic aftermath each believes the other is dead.