How does Odysseus say no to Calypso’s offer of immortality and still not offend her?please help me.

Well, anyone who knows Odysseus knows that he has a clever
tongue.  When he refuses Calypso’s invitation to an immortal life (a tempting offer for
anyone) he seems to pacify Calypso by admitting that the wife he returns to (Penelope)
could never compare to the splendor of the Goddess herself. It may be that this flattery
goes a long way to soothe Calypso.

It’s also important to
note that the speech Calypso makes about the double standards of the gods earlier in
book 5 establishes that she has bigger fish to fry than Odysseus. Her problem is really
with Zeus and the male dominated order of the world she lives in. She may be distracted
from the snub by Odysseus by her greater anger for Zeus, or it may be that she’s to a
degree accepting the order of the world she lives in and not raging against it by
unleashing her frustration on Odysseus. Not to mention, she’s been commanded by Zeus to
let Odysseus go, to disobey would spell great trouble for her.