Actually, it is an argumentative essay as it has a thesis that you attempt to support. It’s also a thesis that has political implications.
Supposedly you support sex between consenting adults and then label sex between consenting individuals as ‘rape’ based some arbitrary standard (which is still undefined). You can’t say things like that and then hide behind the assertion that this is ‘just’ a personal essay. You are calling a certain group of people rapists. That has weight and (legal) consequences