We would like to offer a different answer to the question of the Hafla'ah here, and propose that even though we say כאן נמצא כאן היה with respect to איסורים as well [as we saw from the Magen Avraham], nevertheless with regard to the איסור לבעל that might be generated when he says "פתח פתוח מצאתי", the rule of "כאן נמצא כאן היה" is not relevant.
First - TKO!! [Thinking Kippot On]: In the sugya about nullifying the marriage when the woman is found to be a בעולה, the problem is that there is a "מום" [blemish] in his acquisition. He wanted a בתולה and he instead received a בעולה. PROBLEM!! In contrast, with regard to the question of whether she is אסורה לבעל, the reason for the איסור [affectionately known as "סיבת האיסור"] is NOT that she is a בעולה, but that she engaged in a מעשה זנות - a forbidden sexual alliance. Even if she would have remained a בתולה after the act [which a billion "chaseedei yoshke" believed actually happened once. Don't buy it... It's built on a pagan myth, as we already discussed on these pages], she would still be forbidden. [In fact, if an אשת איש has ביאה שלא כדרכה, where there is no penetration and she thus remains a בתולה (if she was one to start with), that also causes her to be forbidden - :עי' יבמות פרק ו' משנה א וקידושין ט].
According to this it would appear that that only with respect to מקח טעות, we say that the fact that she is found to be a בעולה after her נישואין doesn't arouse a ספק that maybe she was already a בעולה in the רשות of her father. We instead say "כאן נמצא כאן היה". Her status is assumed to have been adopted in this רשות and no other. Whereas with respect to the question of whether she is forbidden to her husband, which is about the עצם מעשה זנות, the very act of promiscuity, finding her to be a בעולה now neither permits not forbids her. For as we explained, her שם בעולה has no bearing on the question of her permissibility to her husband. We just know from the fact that she is a בעולה now that she committed a forbidden act of זנות. Now we have a doubt - When did this happen?? תחתיו or not תחתיו?? Did this happen when they married or not. With respect to the מעשה זנות, it would appear that we can't say that since her lack of virginity was discovered only now in this רשות, we can't have a doubt about the previous רשות. Because the fact is that even in the present רשות, we didn't discover the actual מעשה זנות, all we have is an indication that at some point she did something really naughty. What we see before us is not the actual מעשה but just a clear arrow pointing toward it. To explain further: Let us say that witnesses come after she was married and said that she was מזנה but they don't whether it happened before she was married or after. There we DEFINITELY don't say "כאן נמצא כאן היה". Here also, even though the doubt was brought to the fore because she is a בעולה, that is only like עדים who testified that something happened earlier.
So that explains why we don't say "כאן נמצא כאן היה" when he claims "פתח פתוח מצאתי" but rather permit her because of the famous ספק ספיקא.
[עפ"י תורת מורנו הגאון רבי חיים שמואלביץ זצ"ל]
