Is there someone you have enmity towards? God wants His people to have unity. By not loving your brother, you are sinning against God. Sin against God results in separation from Him. I don't know what grudge you have against the person. I don't know what they did. Maybe they cheated on you. Maybe they lied to you. Maybe they rejected you. Maybe they left you. Maybe they raped you. WHATEVER the maybe, you need to forgive them. Loving someone doesn't mean liking them. Heck- I know there are many people that don't like me. So be it. But God says that whoever loves Him must also love his brother. If the person you hate is not a believer, I still exhort you to forgive them. What they did to you might be unexcusable- it might be painful. But we are called to forgive because we are. Whatever that person did against you, also did against God, and He will bring justice. Forgiveness does not show that you are a weak person, but rather showing humility by forgiving the one you dislike strengthens you, and your relationship with the Father. Forgiveness doesn't do as much for the forgiven as it does for the forgiver. You become released from the bondage of bitterness/hatred/envy. If you are in a broken relationship with another believer, I encourage you to be reconciled in unity with your brother and/or sister in Christ. If there is not unity within the body, the body is broken and will not be able to work as well as the body. Just as if one of your own bones are broken, your body cannot function as it should, so also- if the body of Christ is broken in relationship, it cannot function as it should. Therefore, "If we love one another, God abides in us and his love is perfected in us."
Who do you need to forgive in order to love? This love isn't the type that fancies someone, but rather imitates the love of Jesus for the glory of Him. Matthew 6:14-15 says this:"For if you forgive others their trespasses (sins), your heavenly Father will also forgive you, but if you do not forgive others their trespasses, neither will your Father forgive your trespasses."