What do you think the new symbol of romance in millenial era like this? I want to give my hubby flowers or candelight dinner but it seems so 'boring' nowadays.

I don't think there is any particular "symbol" for romance. For some, a day without arguing and getting on each other's nerves can be considered romantic hahah. If you do want to show romance, do whatever that is sincere to you and your partner. Cheesy as it sounds, it's the thought that counts.