HI Abhishek First let me congratulate you for having such a wonderful person (Who is going to be ur life partner for sure and i will pary for that) to support you at any stage whatever be the situation. Its very much the blessings of neptune the planet of love i suppose that u have been infact GIFTED of such a partner.
Exams comes exam goes ...............But what matters is the support of your beloved one who swears by you at any stage at any time in any circumstances of your life. This should assure you that in future if you face come accross any complex situation then you have a wonderful person to support you at any length.
Degree you will get one day.........Infact You will also get Good Job that for sure..........UR sisters will also be married . because these things are bound to happen ,,But what about her.......Its the only thing uncertain...Make it certain convenience her parents that U will take good care of her under any circumstances come what ever may be.
Do not take the shelter of passing in CA Exams to covenience her parents ......because after all what matters is your love and care towards her and not your degree.