May one eat from non-toveled utensils where the food is all kosher? Do issues such as Shalom Bayit apply (i.e. your parents will not all of a sudden Tovel all of their dishes/silverware)?

According to most Rishonim and Poskim there is a prohibition to use utensils that have not been Toveled. There is a minority opinion that there is a Mitzvah to Tovel, but no prohibition of use. According to some Poskim there is a prohibition, but only for the owner. The majority opinion is that there is a general prohibition. In situations of embarrassment, or for the performance of a Mitzvah (e.g. drinking four cups of wine on Pesach), or when there is another extenuating circumstance, a guest in someone's home may rely on the minority opinion that use for persons other than the owner of the utensils is permitted for the following reasons: 1. It is widely agreed that even if there is a prohibition of use it is Rabbinic. 2. Many materials used for utensils today do not require tevila according to all opinions. 3. Some hold that only utensils owned by a single non Jew require tevila, but that those sold by a company do not. This leniency does not apply if there is no extenuating circumstance. Since there are other factors about which utensils may not be used, a Rabbi should be consulted about particular cases. In any event, the food which was prepared in not toveled utensils is kosher and may be eaten.