(Mishnah): If a person gave flour to an innkeeper's wife to prepare dough, he must separate before he gives her and after he receives it back, as she is suspected of switching it.

(R. Yosi): We are not responsible for swindlers - he must only separate from what he takes back from her.

(Gemara): R. Yosi and Rabban Shimon ben Gamliel both said the same law - just as R. Yosi said that we are not responsible for swindlers, so too Rabban Shimon said it.

It's logical to say that R. Yosi would agree to Rabban Shimon but Rabban Shimon would not agree with R. Yosi. R. Yosi would agree to Rabban Shimon that we are not responsible for swindlers; but Rabban Shimon would not agree with R. Yosi, as it's not normal for a Chaver to give out something that is not tithed.

(Mishnah): If one gives produce to his mother-in-law, he must separate before he gives her and after he receives it back, as she is suspected of switching it if it became spoiled.

(R. Yehuda): (The reason she does this is because) she is concerned for the welfare of her daughter and she is embarrassed of her son-in-law (to give him spoiled food).

And R. Yehuda agrees that if a person gives his mother-in-law Sheviis produce, she is not suspected of switching it and feeding it to her daughter.

(Gemara) (R. Yochanan): Even the first clause of the Mishnah follows R. Yehuda and not the Rabbanan; as R. Yehuda said that giving to his mother-in-law is like giving to an innkeeper's wife. Rabbanan say that giving to his mother-in-law is like giving to a neighbor.

As the Baraisa taught - One who gives his neighbor bread to bake or a dish to cook, he need not be concerned for Sheviis or Maaseros. When is this? When he gave her yeast and spices; but if he did not, he must be concerned for Sheviis and Maaseros.

Question: What type of mother-in-law is being discussed - where he is betrothed to her daughter or fully married to her?

Suggestion (our Mishnah): And R. Yehuda agrees that if a person gives his mother-in-law Sheviis produce, she is not suspected of switching it and feeding it to her daughter.

Conclusion of proof: There, is there any difference between during betrothal and after Nisuin (the completion of the marriage)?! Here also there's no difference between after betrothal and after the completion of the marriage.