彼はいつもつまらぬことでくよくよする。

he; him; his; boyfriend

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

always; usually; every time; never

to be packed (with); to be full (space, schedule, etc.); to be blocked (road, pipe, etc.); to be clogged; to be plugged up; to shorten (width, interval, etc.); to shrink (shirt, word form, etc.); to narrow; to be at a loss; to be hard pressed; to end up; to be settled; to become a geminate consonant; to hit the ball near the handle of the bat

thing; matter; incident; occurrence; event; something serious; trouble; crisis; circumstances; situation; state of affairs; work; business; affair; after an inflectable word, creates a noun phrase indicating something the speaker does not feel close to; nominalizing suffix; pretending to ...; playing make-believe ...; alias; aka; nickname; alternative name; also known as

indicates location of action; at; in; indicates time of action; indicates means of action; cause of effect; by; and then; so; indicates continuing action; indicates certainty, emphasis, etc.

worrying about; moping; brooding over; fretting