Carol muttered:
Yeah, but couldn't Larnie be a perfectly acceptable couple at *some* point?

Not *right* away, but *eventually*...
Eventually? Sure! But Clark and Lara have to be on a firm foundation first. Lara allowed Kryptonian social mores to deprive her of her firstborn. She can't allow her own loneliness and homesickness to lead her into a relationship with Dr. Bernie-Klein before she and Kal-El get righteous with each other. Her priority right now
has to be rebuilding the bridges with her son.
Then, maybe if Bernie isn't too freaked out by the prospect of dating
Superman's mother, they can see what might happen.