Is it normal to dream about another ppl or other strangers in a sexual way (guy dreaming )even when has a gf that he’s attracted to ?

My boyfriend admits this a lot to me and I just want to know if this is common among most men and to be detailed he’s thought about close friends or girls he’s met b4 or just women in general even when he jacks off too and it’s saids it just to go by faster 1.i don’t see myself as unattractive 2.im good girlfriend 3.ive been told I’m good in bed 4.weve been together for a year now