People will let you down, disappoint, and trample you.
As humans we tend to love others when it's easy or convenient for us, when we should love them no matter what. The bible says:
Love is patient and kind; love does not envy or boast; it is not arrogant or rude. It does not insist on its own way; it is not irritable or resentful; it does not rejoice at wrongdoing, but rejoices with the truth. Love bears all things, believes all things, hopes all things, endures all things
1 Corinthians 13:4-7
Love is hard. It's difficult to love people when they are complaining or are having a hard day. But God's love for us is endless. And because He loves us, we should strive to love others. So because of Jesus's example of love, I'll fight to love my brother even when he's being annoying. God doesn't abandon us when we mess up, He still loves and cares for us. So because of that, we should love and care for others even when it's hard.