彼が若いはずがない。

he; him; his; boyfriend

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

young; youthful; immature; green; low (number); small

expectation that something took place, will take place or was in some state; it should be so; bound to be; expected to be; must be; nock (of a bow); nock (of an arrow); nock-shaped grip (between thumb and forefinger); wooden frame on the tip of the mast of a Japanese ship that prevents the hawser from falling out

nonexistent; not being (there); unpossessed; unowned; not had; unique; indicates negation, inexperience, unnecessariness or impossibility; not ...; to not be...; to have not ...