Love is a driving factor of wanting to protect someone. When you care about someone you don't want to see that person hurt or sad. Negative emotions are a part of life though. They're unavoidable and should not be avoided but faced. To bar people from the truth does them a great disservice. Love should not be placating lies but strong support to weather the truth together.
One of the reasons people lie about things is so they don't drag people down with what they themselves are going through.
This is common with people who are suffering life threatening illnesses or life altering occasions, usually ones that include death. Lying allows them to avoid the truth and other peoples pity. The people who are lied to usually get hurt because of this. They want to stand with the person and support them with love and care.
While it's a noble endeavor to protect someone, protecting them from the truth rarely does any good.
There are truths that no one wants to hear like 'I'm the one who crashed the car' or 'you're dad isn't your biological dad because I cheated on him with his brother' but lies like that benefit only the liar and are never used to protect others but themselves. The ones like 'we didn't tell you grandma was sick but she passed recently' or 'your aunt just finished going through chemo,' actively try to protect but they're all selfish lies.
Telling lies, in a way, doesn't protect but coddles. It's not just the lack of trust that stings but the lack of faith that the other will understand, can be strong enough. Tears and sadness do not mean weakness. Being hurt by the truth does not mean weakness. Lies aren't justified because no matter the intentions they're more an insult to a person's courage and resilience than an act of protection.