Part of the process of my better coming to terms with being aromantic involved a fair amount of not wanting to 'miss out' on things like dating and Valentine's Day and all that, but like:
1- Thinking about it those things don't matter as much as I thought they did.
2- There are options which I have considered.
Ultimately those things would likely have ended up with me just playing a role I didn't want to. If I'm going to play a role, it should be one I enjoy, right?
And none of those things are exclusive to romance. Like I can take my friends for meals and send them letters and all that, right?
So much of it is down to other people's expectations, so why not play on them for personal amusement?
Go for that lovely Valentine's Day meal all dressed up but with no expectations, knowing just how people will react to 'such a lovely couple'.
(also maybe getting couples discounts I will always game scenarios for profit sorry)
Buy flowers or gifts for one another and hand them over in public, and see how people cluelessly smile and think they know exactly what is going on.
Act ever so slightly close and affectionate, and watch for the 'knowing' glances and looks, so full of vital misunderstanding.
Play the role, not out of obligation or need, but for entertainment and because it might be fun, and laugh about it later. Let other people be oh so wrong, and have oh such a good time as you do so.