Spenser is writing about love thwarted or unrequited love in Amoretti Sonnet 34. The meaning of "unrequited love" is unreciprocated and unreturned loved: the one Spenser loves loves him not in return. The idea of love "thwarted" is the same: his efforts at kindling love are opposed, success is prevented. Spenser wrote the Amoretti sonnets for Elisabeth Boyle whom he met in Ireland when a widower with two children. He soon fell in love with her, but she, partly because much younger, wanted nothing to do with him though they were often thrown together as Spenser was a friend of her father. The Amoretti chronicle the progress of his love for her and his unrelenting efforts--though thwarted--to court her. As such, what cannot be said of all poetry can be said of these sonnets: The poetic speaker is in fact Spenser's own voice.
Sonnet 34 is written at a period when Elisabeth is being particularly displeased with Spenser, and he feels lost: "do wander now, in darkness and dismay." He needs her love to guide him as a "lodestar" guides a ship at sea: "So I whose star, that wont with her bright ray, / me to direct." “Wont” means is accustomed to: He is accustomed to being directed by “her bright ray.” But for now, since his love is not requited (i.e., not returned in kind), he wanders "carefull comfortless, / in secret sorrow and sad pensiveness." Here, "carefull" means full of care, burdened, which is why he is "comfortless." His sorrow must be secret because he doesn't want to irritate her further or be humiliated: "through hidden perils round about me placed."
To provide some continuity, Sonnet 32 speaks of being unable to soften her stony heart even though fire can soften steel: "her heart more hard then iron soft awhit." Sonnet 33 speaks of the wrong he is doing his Sovereign Queen because he is too distressed to continue his toil on The Faerie Queene: "Empress my dear dread, / not finishing her Queen of faëry." Sonnet 43 speaks of Elisabeth's wrath: he must speak his heart though "her wrath renew I shall." Eventually Spenser wins her, his love is finally requited, and the Epithalamion celebrates their wedding and nuptial bliss.