I have a theory about this.
TL;DR Make a note IN WRITING of your impressions after a first date. Those impressions matter.
I’ve been in five long-term relationships (2-10 years each) in my seven decades of life. One ended in divorce, one in widowhood. The others ended for other reasons.
When you come home from a first date with anyone, immediately sit down and list your impressions, good, bad, and indifferent. What was your first impression-- no analysis, just quickly note down. No matter how small or seemingly insignificant. Welcoming, standoffish, cool, holding back or revealing everything, eager or indifferent. Did you feel drawn to them or a little put off. (NOT about looks, but about physical/energy vibe.) Not judging-- just noting and putting these thoughts on the back burner for now.
Were they rude to the waiter, or considerate? Did they make a fuss about prices or were they stingy, grudging tippers? Did they speak warmly of their family or their ex? If they have kids, what was their attitude toward them? What about pets? Did they mention anything about the past? In a positive way or bitterly? Did they talk a lot about work or seem to avoid all mention of work? Were they interested in YOU and what you had to say or did they hog center stage? Did they answer questions directly or deflect them?
And this is the hard one: red flags. Or even yellow flags. Anything give you pause in even the slightest way? Be honest with yourself before your eyes and heart are dazzled by other considerations.
Just saying, notice your first impressions. Don’t set them in concrete, but take note of them IN WRITING (to yourself) before you put on the rose-colored glasses. Don’t pull a Liz Lemon and slap the “DEALBREAKER!” label on them on the first date (except for a very cogent reason). But keep your eyes open and your heart guarded as you proceed.
If you do get involved and combine your life and your households, I can almost guarantee that if you consult these notes months or years down the road, you will be stunned at the accuracy of your first impressions, for good or for ill.