A trusted wedding planner will keep you from crossing the line into bridezilla territory because they'll handle a lot of the tricky things that typically stress brides out.
Don't get overly rigid about each decision. If your partner wants something different than you planned, take time to think about it before completely shutting the idea down.
Every single day on your calendar doesn't have to be dedicated to planning your wedding. It's perfectly alright to take a few days off every now and then to destress.
Issues with your partner could arise if you can't help from bringing up wedding topics in every conversation. If you talk about the wedding too often, it could lead to burnout.
Grounding practices like deep breathing or taking a short walk force you to acknowledge the present moment which can ease mental discomfort, or even bridezilla mood swings.