the 3 win screens inside of knightfall are obtainable by

-first one where the 2 knights propose with the rose is gained by u and your teammate being alive at the end

-the 2nd win is the gravestone is gained if you or your teammate are dead only of u need to die not the other and if they collect the rose u will get the grave stone ending

-the 3rd ending is gained if your teammate disconnects and u grab the rose it will show the ending of the knight touching the photo with the rose

and that is how u get the 3 endings :) hope u have fun with knight fall and enjoy