Should we care about what others think? If so, to what level? (Most of the time, those thoughts creates suffering).
Maybe if it's people that cares about you and your spiritual progress. Good friendship with good advices/criticism is a treasure to be protected.
In the Dhammapada, we see that:
Should one a man of wisdom meet who points out faults and gives reproof, who lays a hidden treasure bare, with such a sage should one consort. Consorting so is one enriched and never in decline.
Let him exhort, let him instruct, and check one from abasement. Dear indeed is he to the true, not dear is he to the false.
Yes, as long as this would boost the desire to abandon what is unwholesome and undertake what is wholesome.
these two bright qualities guard the world. Which two? Shame & compunction. If these two bright qualities did not guard the world, there would be no recognition of ‘mother’ here, no recognition of ‘mother’s sister,’ ‘uncle’s wife,’ ‘teacher’s wife,’ or ‘wives of those who deserve respect.’ The world would be immersed in promiscuity, like rams with goats, roosters with pigs, or dogs with jackals.
Now if I, having gone forth, were to think thoughts of sensuality, thoughts of ill will, or thoughts of harmfulness: Great is the community of this cosmos, and in the great community of this cosmos there are contemplatives & brahmans endowed with psychic power, clairvoyant, skilled (in reading) the minds of others. They can see even from afar. Even up close, they are invisible. With their awareness they know the minds of others. They would know this of me: “Look, my friends, at this clansman who—though he has in good faith gone forth from the home life into homelessness—remains overcome with evil, unskillful mental qualities.” There are also devas endowed with psychic power, clairvoyant, skilled (in reading) the minds of others. They can see even from afar. Even up close, they are invisible. With their awareness they know the minds of others. They would know this of me: “Look, my friends, at this clansman who—though he has in good faith gone forth from the home life into homelessness—remains overcome with evil, unskillful mental qualities.”’ So he reflects on this: ‘My persistence will be aroused & not lax; my mindfulness established & not confused; my body calm & not aroused; my mind centered & unified.’
Tryin to project one's self-image into the minds of others is a source of suffering1. So one should look inwardly and constraint oneself with the precepts and also develop the Brahavihara and be benevolent. This protects others also oneself. Beyond this worrying about what others think will create misery as this is not in one's control and one's ego is expanding from the spere of "me" to "dear ones" and "others" (also see link below). The misery will be more closer you are to the person in question.
1 This is highlighted in this example: Vipassana | S.N. Goenka | The Ego - "The teacher and his 5 students"
Are you sure about the first sentence? I thought that trying to understand what other people are thinking is good and normal -- that theory of mind is a skill which children develop from an early age. And that it's related to empathy or compassion, e.g. the Dhammapada, "All tremble at violence; all fear death. Putting oneself in the place of another, one should not kill nor cause another to kill."– ChrisW ♦Mar 29, 2020 at 12:54
@ChrisW Doesn't empathy lead to suffering as well, if one holds onto the pain of others instead of accepting it? Even "good" things can lead to suffering if they are approached in the "wrong" way. Mar 31, 2020 at 10:38
1@user29568 Conversely even "bad" things might be handled without suffering if they're approached in the right way -- e.g. tipitaka.net/tipitaka/dhp/verseload.php?verse=124 although that's slightly out of context -- but you might want to ask this as a new/separate question instead of in a comment here.– ChrisW ♦Mar 31, 2020 at 10:46
@ChrisW I just found your question interesting, it reminded me of a question I had a while ago. Mar 31, 2020 at 10:49