It's human nature to compare everything!
If one has experienced something before and then they have it again they start to ponder what is different or is it the same. That goes for relationships, meals, or whatever. Oftentimes it is the "individual" who has evolved or changed.
Being "in love" at age 16 is likely to be different than falling in love at age 26 or 36. Your so called "ideal mate" requirements change.
There is always a "reason" why we say "yes" to one person and "no" to another person. Choosing not to do the introspective thinking to figure out why is up to the individual. Some people find it unromantic to (think). It's important to know yourself thoroughly and be yourself.
Never separate your mind from your heart when making relationship decisions. The purpose of the mind is to protect the heart.
One man's opinion!:)