[link to original on tumblr]
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"A Hard Day's Night" and "Tell Me Why" present opposite outcomes of the same situation. In "A Hard Day's Night," the speaker/singer says, "It's worth it just to hear you say / You're gonna give me everything / So why on Earth should I moan?" There's gift-giving (or even just the promise of gift-giving), so there's no grumbling or animosity, unlike in "Tell Me Why":
Well, I gave you everything I hadHere, there's also giving "everything," but now there is cause to "moan" because the affection isn't reciprocated.
But you left me sittin' on my own
Did you have to leave me oh so bad
All I do is hang my head and moan
"Can't Buy Me Love" presents the same sort of idea ("I'll get you anything, my friend / If it makes you feel alright"), but it also complicates the idea with the titular line: "Money can't buy me love."
Taken together, it seems to present the view that giving "everything" can certainly help a romantic relationship, but it's not the essential element.
EDIT: I forgot to mention that there's also "She gives me everything" in "And I Love Her."