I think it depends on the intent.
You gave three different examples:
1. Girls complimenting each other even if they don't mean it.
Like you said, they don't mean it. When girls compliment each other they almost always do it for one of two reasons;
a: because they want to compete for chad and will lie and gaslight their ugly friends. <---- This is clearly IMMORAL
b: because of social norms, women are very sheeplike/virtue-driven people and will do whatever the 'group' finds normal and morally acceptable, without really questioning it. They will compliment their friends, because it's the nice/good thing to do. Not because they mean it. <--- This is morally ambigious imo, but also lazy and braindamaged
2. Telling terminally ill person they're healthy to make them feel good
Also morally ambigious, the intent is moral (virtue ethicist), but the consequences can often lead to more misery if you think about it which is immoral (utilitarian perspective) (Although sometimes it can lead to a more peaceful death, but you're still stripping the patient of their autonomy which is an arrogant thing to do imo, (why do you get to decide how someone dies when they die))
The deontologist would say however that this is illegal and therefor immoral.
It really just depends on how you look at it, personally for this example I take a utilitarian perspective.
3. Santa claus.
again the intent is moral --> offer your children a higher quality childhood.
However sometimes parents do it, because they want to fit in with the other parents and do it because it's what you do. or because they don't want to be cast out from the social group of other parents.
I think that's usually immoral, because you'll often see parents not being very involved with making santa claus enjoyable.
most children can forgive and understand why their parents would lie about santa though once they develop post convential morality.
All in all, each scenario is different in my opinion. If you take a hardline approach as to whether lying to spare someone's feelings is ALWAYS moral or ALWAYS immoral no matter the context. Then you are taking a kantian categorial imperative. (Deontological)
