First and foremost, it's completely normal to feel jealous at times in your relationship. It's how you handle the jealousy when it occurs that can be healthy or not.
Whether you just had a fight about something silly that sprung up in the moment, or this was something that has been brewing for months, after a fight with your partner, there are things you can do to remedy the situation and hope that it doesn't happen again.
If for one reason or another you didn't plan anything for Valentine's Day yet, but suddenly you find yourself needing plans, I think I have some ideas for exactly what you're looking for!