彼は往復ともタクシーに乗った。

he; him; his; boyfriend

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

making a round trip; going and returning; coming and going; round-trip ticket; return ticket; correspondence; exchanging (letters); socializing; visiting one another

certainly; of course; to be sure; surely; even if; no matter (who, what, when, where, why, how); though; although; without even; without so much as; at the (least, earliest, etc.); also (called); emphatic particle

taxi

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

to get on (train, plane, bus, ship, etc.); to get in; to board; to take; to embark; to get on (e.g. a footstool); to step on; to jump on; to sit on; to mount; to reach; to go over; to pass; to follow; to stay (on track); to go with (the times, etc.); to take part; to participate; to join; to get into the swing (and sing, dance, etc.); to be deceived; to be taken in; to be carried; to be spread; to be scattered; to stick; to attach; to take; to go on