Yes.
I finally found some other forums discussing this, and it looks like it seems kind of random if Sims like gifts or not, which seems like a bug in itself.
Why wouldn't a Sim who has a flower garden like a rose from her husband on Valentine's day? Still seems weird.
I removed all the 'gift giving' traditions from every holiday, because this is so un-fun.
For me, it's not only flower-giving that causes the sims to get negative relationship points; it's any kind of gift. For example, one child giving another child who has the 'geek' trait a voidcritter card caused a mutual relationship hit. I did this multiple times, as I was deliberately giving the cards to npcs (to stack the deck, heh--only it doesn't work that way, rats!), & every time the kids reacted negatively (they knew what I was up to? 👿 ). Curiously, when adult sims gave child sims voidcritter cards, the kids responded positively. ??? Aside from the cards, though, the responses seemed random, & seldom made sense given the relationships & characteristics of the sims involved. Why would an empathetic, polite, etc. sim respond badly to her child giving her a flower? She wouldn't...except in TS4. 😞
I don't care if it's by design: it's a terrible, immersion-breaking design, & needs to be fixed. The various gift/flower-giving traditions aren't worth having until this is fixed.
