Taking partner surname without being married

So I have been with my boyfriend for nearly two years and I want to take his last name but include my mother's surname so it would be wiffen-lyth both are old English surnames but I don't dare ask incase he finds it weird we don't have kids yet but my current surname is my dad's who I no longer have anything to do with as he cheated on my mam when she was dying and abandoned me when I was 15 which ended up me living with my sisters I want to change it because I love him and we do plan on getting married one day but I can't also bare to carry my dad's surname because of what happen and the disgrace of his family and the abuse I revived from my dad and his family what's people's thoughts?