So the sim who received the Faithful (Tulip) Vase can not do romantic socials to any other sim (apart from the Sim they received the Faithful (Tulip) Vase from)?
**Edited to answer anyway for those of you who may not know and would like to...this is normal game play. The scented with Tulip flower arrangement once given, locks the receiving Sim out of any romantic socials except the Sim that gave the flower arrangement to them.
It's a good way to keep sims faithful but you do need level 7 flower arranging skill to be able to scent flower arrangements with tulips. As well as that..the flower arrangements do wither so you would need a supply of them really.