I think the issue is fear. Some people fear choosing the wrong partner to the point of avoiding the choice altogether. They worry that even though they like each other now, will that change over time? How well will the two of them face life’s inevitable challenges?
Concerns about the impact of mental health issues on a marriage can escalate rapidly and horror stories abound.
So, we assure them with advice like have havtacha in haShem and confidence in yourself and your partner, but not everyone’s concerns are so quickly assuaged.