Ok, this is a spoiler, I'll put the answer below
Dalton will reject you no matter what you do on Malcolm's house. Now, If you kiss him, you'll notice that the romance went up. That's your clue to know that he still cares for you. If my memory doesn't fail me, you should have 80 romance with him if you were successful on the restaurant date and kiss him after Malcolm's dinner. You'll get the good ending.
In case you want the bad ending, you should fail either at the restaurant date, or refuse to do anything at the end of Malcolm's dinner.