Stanza 5 Summary

Get out the microscope, because we’re going through this poem line-by-line.

No later light has lightened up my heaven,
No second morn has ever shone for me;

The speaker tells us here that there hasn't been a second lover since her "Sweet Love of youth." So the words "later light" and "second morn" are really just metaphors for a rebound—Victorian-style.
The start of the fifth stanza has got all sorts of rhythmic goodies to enunciate the speaker's faithfulness. The perfect iambic pentameter here highlights the fact that there hasn't been a "second" since the speaker's young love. How perfect, no?
And the anaphora we see in the "No..." clauses also serves to keep things sounding put together and emphatic in their meaning.
There's no doubting the speaker's faithfulness. She really hasn't moved on and found herself another man.
Notice the alliteration in "later, light, lightened." Line 17 is sounding not only emphatic but also mighty poetic with all of those L sounds that catch our attention. Check out "Sound Check" for more.
The metaphor comparing light and morning to love gives us reason to suspect that despite the speaker's faithfulness, she's still without "light" and the joy love brings. So maybe we feel bad for her, but we have to admit that a Victorian audience would applaud this sort of despair as being indicative of a good woman.
From a romantic standpoint, we can kind of understand the applause, too. No one wants to feel as if they're easily replaceable, so the speaker's emphasis on there being no "second light" makes that love appear all the more special.

All my life's bliss from thy dear life was given,
All my life's bliss is in the grave with thee.

The second half of the stanza follows the same sort of pattern as the first half, so the speaker seems to really be driving her faithfulness home here. All of the bliss she got is now in the grave with her lover. There's no gray area here.
And again the anaphora we see in "all my life's bliss" furthers the speaker's sincerity in what she's saying.
We get the sense of the speaker being a sort of martyr here. She's sacrificed all of the joy in her life for her lover by giving him all of her bliss. So this runs a bit contradictory to what we saw earlier regarding "other desires and other hopes." Hmm.
Notice though that there's a difference between words like "bliss" and "desires." Bliss denotes something that's joyful and light, while desire sounds more impetuous and heavy. So although the speaker seems to be contradicting herself, she's doing so in a way that indicates a difference between the various ways to experience life.
We can also understand what the speaker means when she says all of her bliss that she got from her lover now rests with him.
It's hard to feel blissful again once you've lost the source of your bliss. And she seems to have resigned herself to this awareness. We sense a but coming though…