How do you feel about the "Opposite Attracted" sentiment?

It's ok. If you make opposite sims date each other it's nice that they recognise it.

And Sims 4 does have memories since the base game. It's very inconvinient to use and most players don't know it exist, but it does have memories. How it works - you make a screenshot, go to sreenshots and turn a screenshot into memory. You can select whose memory it is. The game can tell if i is a happy memory or flirty or angry.

What memories really need is the ability to filter memories by sim. Than it would work fine.