Scientifically you can attribute it to ‘Halo effect,confirmation bias and positivity bias’.
But in lay man’s terms why anyone would appear perfect to me and vice versa ?
Love begins with basic matching of frequency.Before loving (accepting) anyone we judge our potential partners on many parameter (although unconsciously). To accept any one fully we negate their negative qualities one by one by valid positiveessence we self hypnotize ourselves to our lovers.
Love is an intense emotion.You have to become mentally ,physically,psychologically and spiritually naked in front of anyone before falling in love. To allow such transcendence we must absolutely love any one to the fullest.Thus we drop the negatives and amplify the positives to compensate for this elementary requirement of love.
Hence love is a grand illusion in which two people are connected by ways more than one, to ultimately become one. Two is illusion but one is fact.