The ability of a husband to annul his wife's vows (Bamidbar 30:14) places a great responsibility upon him. His silence is considered an agreement to the vow. Therefore, he bears her iniquity, as if he had compelled her or duped her to sin (Sforno 30:15,16).
Similarly, all of Israel incurred Hashem's wrath when they did not protest against those who sinned with the moabite women, and especially Zimri who sinned openly. Hashem's anger abated when they didn't protest when Pinchos killed Zimri either (Sforno 25:4,11). Apparently, Bnei Yisrael's silence in the face of contradictory events indicates their apathy or timidity rather than their concurrence, and it sufficed to halt the plague.
Even Moshe Rabbeinu delayed rebuking Am Yisroel until just before his death, fearing that it would be counterproductive. Moreover, he began with indirect criticism out of respect (Rashi, Devarim 1:1,3).
These three lessons, gleaned from the three parshiyos read between Shiv'a Asar B'Tamuz and Tish'a B'Av (Bein HaMetzarim - the "three weeks"), highlight a perennial issue which has particular relevance as we mourn the Churban. After all, Yerushalayim was destroyed because its citizens did not rebuke on another (Shabbos 119b).
Rabbonim are required to protest even if the people may not accept the criticism. Yet, if it is clear that a rebuke will be ignored, it is better that the people sin unintentionally (Shabbos 55a, see Tosafos). Clearly, many judgement calls must be made, including, inevitably, mistakes in both directions.
A prerequisite for bringing people closer to Torah is love (Avos 1:15). This love, exhibited by disciples of Aharon Hakohen whose descendants bless us with love, must extend to all creatures (b'riyos), especially those who have strayed and require kiruv. Indeed, imitatio Dei requires that we rebuke those whom we love, as Hashem does (Mishlei 3:12), out of concern for their welfare.
In order to succeed, this love must be mutual. We are advised to love rebuke and the person who offers it. The existence of tochachah in the world leads to blessing and the elimination of evil in the world (Tamid 28a, see Rosh).
In a world full of evil, including the crisis in Eretz Yisrael, and at a time that the Churban is on our minds, we can help by offering and accepting appropriate tochachah, given and received with love. The reversal of Sin'as Chinom and 'Lo Hochichu Ze Es Ze' which caused the Churban will reverse the course of history and bring us the Geula Shleima.