I thought I saw something about this same issue elsewhere, but I can't seem to find the thread, so if the thread is found, please combine this post with it, thank you.
So, I started a new game in Riverview. My founder female sim wanted to get 'friendly' with an elder gent, and chose Norman Joy as her potential partner.
She met and befriended him (perhaps best friends), and thanks to her childish trait played tag with him and his daughter, Elaine. Once she was best friends with him, she stopped the games and focused on romantic interactions. No matter what she did her romantic relationship with him remained at 'ok'. She would flirt/tell flirty joke, it would flash up 'flirty' briefly but then returned to 'ok' status. It was the same regardless of whatever romantic interaction I tried. They did not become romantic interests.
I also tried resetting my sim and the entire town, no luck. I did everything I could think of other than, inviting him and Elaine to move in (without getting married), reinstalling game and clearing the caches.
I've since then tried another single sim in Sunset Valley without family baggage to romance the elder (and happily married) Buster Clavell. Not only are they romantic interests, but my sim is pregnant by Mr Clavell.
