1)X and Y miss/misses you. 2)Their courage and patience know/knows no bounds.
In #1, X and Y, presumably people, are separate individuals. 'X and Y' together make up a plural subject. The verb-form is 'miss'.
In #2, it is possible to think of 'courage and patience' as one combined virtue, and use the singular verb-form 'knows'. I, personally would use only 'kno