“先有好感”可以表达为 "develop a good impression first" 或 "have a positive feeling towards someone initially"。
1、 We developed a good impression of each other first before becoming close friends.
(我们先对彼此有了好感,之后才成为密友。)
2、 I had a positive feeling towards her initially, which eventually grew into love.
(我先对她有了好感,后来这种好感发展成了爱。)
feel an instant attraction(瞬间产生好感)
get a good vibe from someone(对某人有好的直觉)
have a soft spot for someone(对某人有好感)
根据语境选择最自然的表达即可!