Be kind, but only as kind as you actually are. Kindness out of compulsion has had horrible effects in my life at times, because of its conflicts with honesty.
Keep in mind, this is mainly an overcorrection from being a timid kid, but what I’ve learned is that I would act kinder and say kinder thing than I harbored inside. I thought it was “Tact” but really it was fear of being honest. I created a mountain of kind words to block out reality. Reality will always come back to you.
I spoke kinder words to my girlfriend than the thoughts I had of her at times. These little lies added up, when I was annoyed or upset, I would smooth it over, assure her she’s not doing anything wrong. But there was, I had been denying my own opinion in the relationship, the truth was, some of the things she would do did upset me. Compounded over many times, this created distance. Distance which she felt, and had to fill in with presumptions of her own. Many of them worse than the small lies I told to remain “kind”, not because they were worse, but because she had to come up with it, rather than getting satisfactorily straight answers from me.
This deeply triggered our Attachment styles, and had a negative compounding effect. Where even though I thought I could make things better by being kinder, I was still pushing her away. This doesn’t make her innocent. I had concerns about being honest, some of it is disposition, but some of it was learned behavior from being snapped at during attempts of honesty.