PAA,
Fakert, Tosafos’s question is much better according to me. I think I might not have been clear enough. Zivug sheini does not mean Second Marriage. It means Second Match. A person has a predestined match that is set well before he or she is born. That is your first match. However, because Ain Mazal L’Yisrael, you can break that destiny and thereby warrant a new match. This new match is not predestined at all and requires Hashem to rework creation. I am happy that I was mechaven to the Beer Sheva and the Chasam Sofer b’shem the Arizal. I think this is pashut pshat.
Asks Tosafos, if that is the case what is the Gemara’s question on Shmuel in Moed Katan, because a person does not know if he has earned a second match, one that is not predestined, he should absolutely be permitted to be m’arus on Cholo Shel Moed because maybe this girl is his zivug sheini. That is a very good question.
Ma shein kein, if you learn that zivug sheini means a second marriage Tosafos’s question is very weak. The mashmaos of Shmuel’s statement in Moed Katan, and the halacha, is in no way limited to someone’s second marriage. It is therefore not surprising that the Gemara did not want to use this answer.
(I am maskim that the Tosafos Shantz is saying not like me, but I think that Rashi and Tosafos are like me)