Sure, Sonnet 55's a love poem, but this speaker's idea of love is no live-in-the-moment, carpe-diem, let's-get-down-tonight kinda feeling. It's not even about tying the knot and living happily ever after in a one-bedroom apartment. This love is about the persistence of memory and the chance of the beloved achieving eternal life. You get the idea that the speaker wouldn't even mind if he never got together with the beloved. This kind of love is too pure for that lust stuff and his poetry is too powerful. He wants "live forever," not "love forever." Sound ambitious? Well, friends, you haven't met Shakespeare.
Smooches to the back of the line. Sonnet 55 celebrates a love that is more concerned with memory than with physical passion.
Art is the only way for memory to outlast death. So get on those poems, gang.