Love how this is put together. The verse is twenty bars long and goes through seventeen chords, with a total of six lines of poetry. Twenty and six, of course, don't make for "square" structures the way that a number like eight or sixteen does. Here, line one and line two are each four bars, perfectly squared, but then line three is only two bars. Its rhyming line, line four, extends that so the last note falls on the downbeat of a third bar. Then there's a rest through the remainder of the third bar plus an additional fourth. That squares things off somewhat, but you've still got the irregularity of lines three and four adding up to six bars total. Same thing happens with lines five and six.
The extension that happens in line four creates a sort of ellipsis where things still need to move in order to resolve, but the lyrics here (as well as the seeming attempts to make this song fairly normal as a structure) are already dictating that we are nearing the closing. Songwriters Barry Mann and Cynthia Weil keep the flow of chords going, but use a classic I-vi-IV-V-I progression in order to quickly bring things to an end. Dropping this standard harmonic sequence all by itself at the end of the verse definitely seems unusual, but the sweetness of these chords really amplifies the sweetness already established earlier in the verse.
The flow of chords in this song continues through the chorus, a second verse and chorus, and then into the bridge, where we get derivations of chord progressions heard already, first sounding like an instrumental passage but then metamorphosing into a vocal bridge. Here, the I-vi-IV-V-I progression is used once again to bring things to a close, and claimed even more so than it was the first time.
To claim such a thing, of course, is bubblegum.