My male jr grawling to our suspected pregnant jr x border collie bitch

by Cathrine Grimsey
(Essex)

We think our jr x border collie is pregnant by our jr terrier, why does "he" growl when we show "her" attention...but when we show him attention she always wants to be in on it to and he growls. We don't know what to do because he growls and she gives a little bark, its a little worrying because we cant show them attention unless me separate them, could this be because she pregnant? or could it just be jealousy?
thank you <3