It’s not true we can’t have friends who are not Witnesses and that it’s looked down upon. Though, we are cautious in who we choose as friends. We relate our lives according to the Bible—which is a beneficial guidance from Jehovah God (2 Timothy 3:16). Jehovah as a loving Father gives loving warning, such as in 1 Corinthians 15:33, mentions, “Do not be misled. Bad associations spoil useful habits.”
In order to stay in Jehovah God’s love and maintain a good relationship we need to be cautious in who we choose to associate so we won’t falter and make big mistakes because of group influences or oppressions.
But what if the associations are good, you may ask?
Good associations are difficult to find sometimes but not impossible. We always have in mind, that people who don’t live by Bible standards don’t love Jehovah God. Thus, they wouldn’t quite support or strike the common goals we have which is to honor Jehovah God. On the other hand, we love conversing with other people—-well it helps us to learn more about them and get to know well our neighbor and love them. :) Then we are able explain to them why we choose to live by Bible standards.—2 Timothy 2:25.
Hope this answered your question :D