If you leave Ayla with Frog, Ayla will eat Frog. Leave Frog with Magus and Frog will kill Magus/Magus will kill frog/manlove will occur.
Soo take Frog across first, drop him off, go get Ayla, drop her on left side and pick up Frog, drop him on the right side and pick up Magus, drop him on left side, then go get Frog and COMPLETE.
Though I probably forgot a rule, like Ayla will molest anyone she's left alone with...