Simplify the following text for a Grade 6 native English-speaking person.
Original: For another Countess of Boulogne named Matilda , see Matilda II , Countess of Boulogne .
Simplified: Queen Matilda of Boulogne ( 1105 â `` May 3 , 1152 ) was the wife of Stephen of England . She also became the Countess of Boulogne when her father died in 1125 .