וַתֹּ֤אמֶר רִבְקָה֙ אֶל־יִצְחָ֔ק קַ֣צְתִּי בְחַיַּ֔י מִפְּנֵ֖י בְּנ֣וֹת חֵ֑ת אִם־לֹקֵ֣חַ יַ֠עֲקֹב אִשָּׁ֨ה מִבְּנֽוֹת־חֵ֤ת כָּאֵ֙לֶּה֙ מִבְּנ֣וֹת הָאָ֔רֶץ לָ֥מָּה לִּ֖י חַיִּֽים׃
Und Rebekka sprach zu Isaak: Mir ist mein Leben zuwider wegen der Töchter Chets; wenn Jakob auch eine von den Töchtern Chets zum Weibe nimmt, von den Töchtern des Landes, was soll mir dann das Leben?
Rashbam on Genesis
If Yaakov marries. This was a stratagem to distance Yaakov from Eisov without revealing to Yitzchok the reason for it.
Or HaChaim on Genesis
קצתי בחיי. "I am fed up with my life." She did not want to reveal the true reason for her state of mind because it is forbidden to tell tales. This is why she gave Isaac a different reason for wanting Jacob sent away. When she had revealed Esau's intention to Jacob this was not tale-bearing but was fulfilment of the commandment in the second half of the verse dealing with tale bearing, "do not stand idly by when the blood of your fellow man is being shed" (Leviticus 19,16).