彼はあやうくおぼれるところだった。

he; him; his; boyfriend

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

dangerous; risky; hazardous; perilous; precarious; in danger; in jeopardy; critical; grave; at risk; uncertain; unreliable; insecure; unsteady; doubtful; close (i.e. a close call); narrow

to drown; to nearly drown; to sink below the surface (of water); to indulge in; to lose one's head over something; to wallow in

place; spot; scene; site; address; district; area; locality; one's house; point; part; space; room; whereupon; as a result; about to; on the verge of; was just doing; was in the process of doing; have just done; just finished doing

be; is; indicates past or completed action; indicates light imperative