It can involve affection as we work together in Christ, but affection is not a necessary element.
We are commanded in the Scriptures to show love to all believers, but we are not commanded to make all believers our friends.
This liking involves a "friendship kind of" affection based often on personality and common likes and interests.
Brother-sister relationships in Christ involve two foundational elements, commitment to fulfill the responsibility of a fellow-believer in Christ and care and concern a believer is to have toward other believers.
There was a time when I wouldn't admit what a sinner I was.
But my dishonesty made me miserable and filled my days with frustration. My strength evaporated like water on a sunny day until I finally admitted all my sins to You and stopped trying to hide them.
Gen. says, "For this reason a man will leave his father and mother and be united to his wife, and they will become one flesh." This verse tells us that marriage involves the husband and wife severing ties of intimate relationships with parents to cleave to each other.
It involves coming together into a permanent bond of unity.
However, the Bible does describe three kinds of relationships with the opposite sex and gives certain characteristics of each relationship (there are others such as parent/child and sibling, but they don't clarify the issues of dating).