Every stanza here starts with the same phrase, "Never has anyone ever," and that repetition does a lot of the work. It sounds like someone counting up all the things they've never had before, and then realizing that one person has finally given them every single one: a compliment, love, humor, steady company.
The speaker feels grateful, a little shy, and slightly amazed. The line "I still can't believe it's you" captures that disbelief well. Good things haven't come easily in the past, so happiness arrives with a trace of surprise. Still, the ending adds a quieter note. Saying they feel "incomplete" when the other person disappears suggests how much they now depend on this presence, and maybe a fear of losing it.
The mood is warm and tender, but also a bit vulnerable. It reads like a simple, honest confession of how much one person's attention can change someone who has gone without it.