彼が来るとパーティーが台無しになる。

he; him; his; boyfriend

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

to come (spatially or temporally); to approach; to arrive; to come back; to do ... and come back; to come to be; to become; to get; to grow; to continue; to come from; to be caused by; to derive from; to come to (i.e. "when it comes to spinach ...")

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

party

mess; spoiled; spoilt; (come to) nothing; ruin

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 become; to get; to grow; to be; to reach; to attain; to result in; to prove to be; to consist of; to be composed of; to succeed; to be complete; to change into; to be exchanged for; to play a role; to be promoted; to do ...