When Marshall accepts the Judgeship without telling her (which is wrong, I admit, but it did require an immediate answer) they get into this big fight, with her just screaming ITALY ITALY ITALY and not letting Marshall say his side. It culminates into this, pictured above.
Lets tally up all of Lily's selfishness so far
-Leaving for SF
-Credit Card Debt
-Guilting him for liking his job (twice)
-Constantly berates him for doing anything that's for himself, not for her
-Picks a sketchy gyno because she's obviously unprepared for pregnancy and wants to get away with doing things
-Putting Ted and his colleagues in jeopardy because she got her feelings hurt
-Stealing a priceless ashtray because she got her feelings hurt
When Marshall calls her on the biggest one she just says "I already apologized for that", but NO LILY THAT DOESN'T NEGATE IT. And she storms off. Because, although Marshall is wrong for taking the job without telling her, and going back on his word, he did it because it would provide stability for his family, not to mention Lily. Lily just yells that he's killing her dreams, proving that Italy, and obviously SF was a selfish thing.
doesn't matter. would still do