How to convince parents - mother who is ill - can't give her shock

Im 21 years old and my boyfriend is 23 years old.we are in a relation for 6years and we are madly in love...actually once we had situation where his mother saw my message she asked him but again did not prolong it and she know that i was the girl who messaged him.i have met her talked to her also,went to their home as his friend..she is having health problem,she has once met with a minor heart attack,so we are scared to say her about our relation,and we truely don't wanna get separated..we have not yet confirmed whether she remember that he was in love n i'm that girl,but since her health is not good and doctor has advised to not to say any shocking news to her,because there are chances of getting brain stroke,he is scared of talking to her about this matter..please give us how we can approach her or any other way where this matter can reach his parents in a good way and success our love story

You may get good chances to get married to this boy, all you need is to be regular at his home, befriend with his Mother. All you have to do is that instead of seen as friend of this boy, be friend of his family. You may befriend with his sister and then visit his house regularly, pay special attention to his mother. Try to find some hobbies or subject which her mother loves, it will be way to get friend and dear to hir mother. Chances are that his mother herself may see a bride in you.

But be thoughtful, don't make it stupid that they realises your intention easily.

Good luck.