30:15. How could Leah say הַמְעַט קַחְתֵּךְ אֶת אִישִׁי? It seems like a caricature of ingratitude for Leah to resentfully say that Rachel had taken away her husband, when in fact it was Leah that took away Rachel's husband, and even that was done with Rachel's help. Even assuming that the switch of Leah for Rachel was done unilaterally by Lavan, and Leah had no choice in the matter, but the fact remains that Rachel voluntarily gave Leah the simanim at the chasuna to prevent Leah’s embarrassment, and if not for that act of kindness, Yaakov would have realized he was being defrauded, he would have kicked Leah out of the tent in middle of the night, and she never would have married to him.
1. Someone answered that the Gemarah (Reb Chiya) in Kesuvos 59b says, women live for two things; their spousal relationship and their maternal relationship. (This is an excellent pshat in the Gemara, but it's not pashut pshat.) Leah said, our husband Yaakov’s personal relationship is already exclusively yours. I am left only with the relationship I have with my children. Now, you want to insinuate yourself into my relationship with my firstborn son Reuven? In other words, Leah was not saying that Rochel had already done anything treacherous by taking her husband. She knew that Rachel had gotten her married to Yaakov in the first place. She was just saying that since her husband didn’t love her (since he loved Rachel), she had only one source of emotional satisfaction in life, and that was her special relationship with her children. If Rachel were to interfere with that, Leah would have nothing left.
2. Rabbeinu Bachaya– Rachel was the Rambam's Baalas Chessed. The Rambam says a baal chesed should give tzdaka so that the recipient doesn’t realize that the other person gave him anything. So when she gave the simanim to Leah, she didn’t say “I am sacrificing my happiness to prevent your disgrace.” Instead, she made up a story that made Leah think that by taking Rochel’s place at the wedding, she was doing Rachel a favor. Maybe Rachel told her she was afraid of Yaakov, maybe she told her she didn’t like him. In any case, Leah was convinced that she was the baalas chessed who had done a favor for Rachel, and that Rachel later cheated her out of her husband by taking his love from her.
3. Reb Yerucham says that once Leah and Yaakov were married, nothing that brought them to that position mattered: it was bashert, and Leah was his intended wife. The factors that implemented that result were completely fungible, and if Rochel hadn’t given the simanim, something else would have happened to ensure Leah’s marriage to Yaakov. (This is a classic strategy, which I have seen in countless meshulachim, of avoiding hakoras tov, along with “you were just doing your mitzvah." I don’t know if Reb Yerucham meant it to illustrate bitachon in hashgacha pratis in marriage, or he really meant that you don’t have to appreciate a gomel chesed because the result was bashert anyway. I hope not. But it sounds like a good excuse not to come up with shadchonus money after the couple gets engaged.)
4. A commenter (The Great Unknown) sent in the following. I hesitated to post it, but, as he said, it's not up to me to censor the words of the Litvishe gedolim
The Maharil Bloch said: " appreciating a favor does not include repaying it in such a way as to nullify the original favor." (clumsy translation of the Yiddish) This was in the context of his firing Reb Leib Chasman immediately after Rav Bloch took over the yeshiva on Reb Leib's recommendation.