It’s entirely possible your boss called ethics to protect himself.

Once you are a boss it is your responsibility to maintain a degree of conduct. Your ethics must be held to a higher standard, and questions being raised can become a rumor and a reputation very rapidly.

There is no way of knowing once a subordinate has confessed feelings to you whether or not they will make a claim against you out of retaliation for unreciprocated feelings or whatever reason.

The safest thing to do is to document as much as possible and go to ethics for guidance.

I’m not saying what I think happened to you was right, or okay, or that these standards are reasonable, just trying to give a (greater benefit of the doubt) possible scenario

I'd ask for the accusation details from HR or the case lawyer (however you call it). Your side of it is obviously very biased in your favour, so it could be your manager has noted other instances you've made them uncomfortable. It should have been brought to your attention before sacking you, but it could be the way you went about it was considered serious enough to let you go

ETA you'd be better asking in r/legaladvice