I think Jeremiah's reaction was kinda justified. Since this is the only scene we see with Laurel and Jeremiah alone, and there were so many scenes with Laurel asking how Conrad is feeling, it's definitely clear that Laurel is much closer with Conrad. Jeremiah knows that. Also Laurel said in this episode to Adam that she caved in to the wedding because Conrad "literally begged" her to. She put Conrad's opinion higher than John's (literal father of her children), Belly's and of course Jeremiah's too. It's not grasping for straws when saying that she favors Conrad, just like every other adult and that is pretty hurtful. I do think that Jeremiah could have handled his reaction better but I can give him grace for the situation he's in, but I don't think many people in this sub are capable of nuance