This personally wouldn't bother me at all, if I was dating someone who was married and considered his marriage his 'primary' relationship.
How often do you get to see him? Do you feel like he blows you off often? What's the underlying issue?
I don't think that there is a "typical" way of things happening in poly. I think it depends completely upon your personal arrangements and agreements.
Sometimes my girlfriend solidifies dates with other people without discussing it with us (her husband and I), but most of the time she pencils in a date with them and then mentions it to us. She does that to be considerate of us and to make sure she doesn't double book.
Are you feeling like you come second, after your boyfriend's wife? Do you not like being second? Do you have a casual relationship or something pretty serious?
Me: (30f) open poly
GF: (40f) My long-term, long-distance partner
Hubby (37m): GF's husband
Garcon (26m): GF's submissive/third partner
“Peace comes from within. Do not seek it without." ~ Buddha