Is it permitted to kiss (one’s wife or somebody else) on Yom Kippur?
Answer:
One must not kiss one’s wife on Yom Kippur.
Although the principle prohibition is on marital relations, as ruled by the Shulchan Aruch (615:1), the Shulchan Aruch adds that a person must not sleep in the same bed as his wife, and the Mishnah Berurah (based on the Magen Avraham) adds that a person should likewise be careful to uphold the other harchakos that are customary when a person’s wife is a niddah (the Mishnah Berurah rules that this applies even during the day, and not only at night — though others (Taz) are lenient).
For people other than one’s wife there is no special restriction.
Best wishes.