I love my aunt but her love is lessening for me?

I am 21 n c is 30. One day i went to my aunt's home.i found her alone, i had to stay there at night. We were on same bad. At mid night i felt naked myself and i found her naked too, c was was lookin too hot, i cud not stop myself and grabbed her into my arms and we started having sex. I really enjoyed that night and after 3 months we had sex again. We had sex only 3 times. Now it has been 2 months but no sex took place btween us but we speak on phone daily for hours. I realy take care of her becoz her husband is no more nw. C wants to get a job bt c is not so educated and m handling her all expenses. This year i arranged money and gave her chance to study abroad. Now it seems that c is nt happy, i asked her that why c was sad then c answered that nothing but i think that there is somthing whch c wants to hide or her love is lessening for me but i never tried to hurt her,even not for a short while. We never had a qurll. What shud i do? I realy want to support her heartly. Help me, help me, help me