Optics just means how it looks. Ignore that, is my opinion.
You say you will get married in mid 2025. Make sure you've spent enough physical time together.
Write a short letter of explanation about the timeline. Stick to facts, dates, times you spent together. Address the breakdown of the previous relationship and the time you spent residing together (with ex/with new partner) while/after the relationship broke down. Do a draft now and add/revisit it later. They don't want Dostoyevsky, just facts.
There can be lots of moralizing about these things and comments about optics but ... s*** happens. They're not doing the sponsorship evaluation to decide why your previous relationship went bad or assign blame, just that it's over, that you didn't misrepresent anywhere, and that the new relationship is genuine.