Question: I married the son of my maternal uncle, and I love him and he loves me. Only six months have passed since we got married, and everytime we go to sleep he grabs hold of me and begins sucking my breasts like a baby, so I said to him: “This is wrong!”. However, he did not stop and I did not try to make it difficult for him.
Response: There is no harm in this, because it is for the married couple to enjoy themselves with each other in other than that which Allaah has prohibited.
This includes sexual intercourse in (her) anus or sexual intercourse whilst she is on her menses or in the state of post partum bleeding or in an act of worship within which sexual intercourse is haraam, or when he has pronounced his wife haraam upon himself until he pays a kaffaarah, and similar to these from those known aspects according to the people of knowledge where sexual intercourse is haraam and in it entails harm for the married couple.
Shaykh Ibn ‘Uthaymeen
Fataawa az-Zawaaj wa ‘Ishratun-Nisaa. – Question 79, Page 109