"But then" appears twice in these twelve lines, and each time the ground gives way. The first time, someone else rearranges the speaker's world: he gets a girlfriend. The second time, the speaker does the rearranging alone, and the verdict is brutal. All we have about the writer is a username, lilacprincessx, so the best way in is through the page itself, and the speaker should be treated as a voice in the poem rather than a stand-in for a real person.
On the surface, this is about unrequited feeling. The poem never says what the speaker and "he" were to each other. It says only what he did: he "makes me feel special / Like I mean something." That second line is more fragile than it first looks. The word "like" suggests that the feeling resembles meaning without being guaranteed, and the speaker's sense of worth is something he hands out. When he moves on, the supply seems to go with him.
The middle of the poem is built on a quiet parallel. He "makes me feel special"; a few lines later he "makes her feel happy." The verb stays the same and only the person receiving it changes. Between the two come "kisses her / And hugs her / And makes her," a chain of "ands" that piles up his affection one gesture at a time. These are things seen from outside, whether the speaker witnessed them or only imagines them, and the pile of them reads like an inventory of what the speaker is missing. Then comes the plainest line in the poem: "I want to feel happy too." The smallest word in it, "too," is the saddest. The speaker doesn't ask to replace the girlfriend, only to be included. A full stop closes the line, and the wish goes no further.
The final turn is where the poem's real subject shows. "I realize" is the language of discovery, as if the speaker has found out a fact, but what follows is a feeling dressed up as one. The three "that" clauses escalate. First, "I don't deserve it." Then "he is so perfect." Finally, "no one wants me." The poem slides from one specific boy to the whole world in two lines, which is how hurt often reasons: one loss becomes a universal ruling. The title's "it" is never defined. It could be happiness, him, or love, and the vagueness lets the idea of being undeserving spread over all of them.
Punctuation helps with this. Full stops land on the two moments of plain fact, "He got a girlfriend." and "happy too." The last three lines have none. The thought isn't resolved, and nothing in the poem suggests it will stop.
The form fits that unfinished feeling. There is no rhyme and no regular metre, just short lines of everyday, mostly one-syllable words like "lots," "kisses," and "hugs." The poem sounds like speech, or like a thought typed fast, and the stray "Hie" in "Hie kisses her" adds to that unpolished feel. "But then" sits alone on its own line, a held breath before the blow. The three lines about kisses and hugs run on quickly, almost without pause. Apart from the one simile, there is little decoration. The poem's pictures are small physical acts, and their smallness makes them hurt more.
What makes the poem worth reading is how little it blames anyone. The girlfriend has no name and no description, and the boy is "perfect" rather than cruel. With no villain to be angry at, the pain turns inward and becomes a judgment on the speaker. That move is easy to recognise, and the poem lays it out step by step. It also invites a reply. Being passed over by one person is not a measure of someone's worth, and the poem's logic, which jumps from "he chose her" to "no one wants me," has a gap a reader can see even when the speaker cannot. The poem does not close that gap, and its honesty is what makes it moving.