Check out this article from the huffingtonpost.com written by Jonathan which states that the public is more fearful of marriage due to seeing failed marriages among celebrities. Ways to ensure successful marriages include: looking at successful relationships and model yours after them, enter 100% committed, know arguments are normal and will happen, and make sure to plan date nights out so you both have something to look forward to for days at a time.
Some good points on overcoming the fear of marriage:
Jonathan Alpert: How To Overcome The Fear Of Marriage

