maybe these ayahs and hadiths could help you inshallah!
"
And among His signs is this, that He created for you mates from among yourselves that you may dwell in tranquillity with them and He has put love and mercy between your hearts: verily in that are signs for those who reflect." (Surah Al Rum 30:21)
Prophet Salallaahu 'aliahi wa'sallaam said
"one would be rewarded for anything that he does seeking the pleasure of Allah even the food that he puts in the mouth of his wife."
Prophet Salallaahu 'aliahi wa'sallaam said
"the best of you are those who are best to their wives."
Prophet (sallallahu ‘alayhi wa sallam) said: “
This world is just temporary conveniences, and the best comfort in this world is a righteous women.”
Prophet (sallallahu ‘alayhi wa sallam) said:
“If a woman prays her five daily prayers, fasts her month (of Ramadan), obeys her husband and guards her chastity, then it will be said to her: ‘Enter Paradise by whichever of its gates you wish.’”
oh...and lots of duas and blessings for your sister and her husband-to-be.