I can relate. It's uncomfortable when someone is ignoring you specially if you see them daily and you have no idea why they ignore you. In my case, I just try to avoid having to talk with that person because it is really awkward. You really can't please everybody. The teaching to love one another was directed to christians who love the Lord because even God does not force us to love him. We cannot force those people who don't know God to show us love.