Data Modeling

Hi Everyone , I am looking for a clarification in data modelling in power BI.

I have two tables i want to build a relationship between.
One is fact table with all the business values and another one is dimension table.

I have one  column in fact table which is named Question_option_field and has Field name values (distinct values - 214, total rows - 19000) and another column in dimension table named Question_option_field for those Field Values
The catch here is that the dimension table column which i want to connect with the  Fact table column has not all the distinct values (so it only has some values of Question_option_field(field names , around 150 distinct and unique value).
When I am trying to create a relationship between them , it is showing me many to many relationship where it should have one to many relationship.
I want to ask is it happening because i dont have aal the distinct values of filed column in the dimension table column or is there some other reason?? Also does it effect my report??