My stats:

maternal grandparents always had twin beds side by side; married for more than 50 years until grandfather passed away at age 80; grandmother lived till 94

paternal grandparents always had one big bed; married for more than 50 years until died in old age, almost on the same day

my parents had different bedrooms because my dad liked smoking in the bedroom and my mom did not tolerate that; he would come to her bedroom in which she had a full bed to have sex with her; he himself had a twin bed; eventually they divorced

aunt and uncle on the maternal side: had a big bed in the apartment and two twin beds in their summer house; married for decades and decades until he passed away (Parkinson's).

So according to my stats, it has no relationship on the outcome of marriage.