Re: Romance social interaction not showing up
Is this happening for all of your Sims or just this couple? What are the traits of the Sims? (Some traits make romance more challenging &/or different, but I've never dealt with any that gave no romantic options, unless the relationship and romance are too low.) What is their friendship & romance (pink) bar level? Is either of them not interested in the opposite sex, in a different relationship, etc.? There is some good romance information at this link: https://www.carls-sims-4-guide.com/relationships/romance.php
Do you have Mods/CC? If so, did you test if the issue is gone without them? (Directions for this in spoiler tag , if you need them.)
Spoiler
Exit the game. Move the Mods folder from your "The Sims 4" folder [Documents > Electronic Arts > The Sims 4] to your desktop (save it for reference) and delete the localthumbcache.package file in your “The Sims 4” folder. Then check in a new game save to see if this issue is still occurring. You can then test without saving – or in a new vanilla game save – in order to identify which CC/Mods are causing the issue. Then remove or add updated version(s) of the Mod/CC causing the issue.