The poem is a single sentence, and it holds one small moment: the speaker looks at someone they love and feels it all over again. The trigger is "the glimmer on his face." We aren't told what causes it. It could be sweat, tears, sunlight, or a certain look in his eyes. Leaving it open lets us imagine whatever light we like, and it suggests the speaker is moved by something ordinary and fleeting rather than anything grand.
The verb "provokes" is an interesting choice. It sounds almost like a challenge, as if the speaker can't help themselves and the feeling arrives without permission. "Still" and "again" tell us this isn't a new romance. Time has passed, and the spark hasn't faded. The mood is tender and quietly amazed, with a hint of helplessness. The speaker isn't deciding to love him; they are simply caught, once more, by the sight of him.