MUNIFICENTISSIMUS DEUS Pope Pius XII
"45. Hence if anyone, which God forbid, should dare willfully to deny or to call into doubt that which we have defined, let him know that he has fallen away completely from the divine and Catholic Faith." [http://www.ewtn.com/library/PAPALDOC/P12MUNIF.HTM]
>>The Apostles likely wouldn’t have taught the Assumption, as many had been martyred prior to her death. Because an exact date is not recorded, we can’t know for sure, on that point.<<
So you don't believe what the Catholic Church puts out about all the apostles being transported to here death bed?
If one doesn’t believe in the dogmatic teachings of the Catholic Church, then reasonably they have fallen away from it. That doesn’t mean they have lost the gift of salvation, given once and for all by Jesus Christ. Instead, it is a teaching binding upon Catholics.
The Church doesn’t definitively teach the Apostles surrounded Mary at her earthly death. There is a vision of this by St. Anne Catherine Emmerich. Hers is a private revelation, which is defined as that there is nothing in them contrary faith or good morals, and that they may be read without danger or even with profit; no obligation is thereby imposed on the faithful to believe them. Further, Benedict XIV says: “It is not obligatory nor even possible to give them the assent of Catholic faith, but only of human faith, in conformity with the dictates of prudence, which presents them to us as probable and worthy of pius belief)” (De canon., III, liii, xxii, II).
While a Catholic is free to believe the Apostles surrounded Mary at her death, it is not required. In my personal opinion only, I just don’t know, and take no stand one way or the other.