Isn't it that amabunt is future indicative form, so meaning 'gods are going to love you', and ament is present subjunctive form, I would take it as ''may the gods love you.
Checking PHI, ament is more common (at least 30+) than amabunt (9).
I haven't checked the uses, but maybe it depends on the type of character and context (e.g., boastful/bragging). Or just a less common variation with no other reasoning.