Blood compatibility (Rh)

Hellow...hope everybody here is doing fine....

Well i have a question...i've heard about if 2 people that are not compatible in the blood types then they should not be able to get marry or have kids...so my bf is negative and i have to be positive cuz both my parents are...so what they say its just in case the baby have the dad blood type and its not compatible with the mother it could cause problems to the baby...so i was wondering if thats true and if it is how really works...

Thank you
Hugs

unicorn22