我让你失望了吗？我让你伤心了吗？为什么你不再爱我？

失望is a verb. it means lose hope or confidence. in english, you say i disappoinrted you,didn't i?but in chinese, we say 我令你失望了吗？我使你失望了吗?我让你失望了吗？in these sentences, "令、使、让"means make.I make you feel disappointed.,do i?让in chinese grammar,the pivotal sentence is also a sentence with a verbal predicate.its predicate is composed of two verbal phrases.the object of the first verb is simultaneously the subject of the second verb.the first verb in a pivotal sentence should be a verb with a meaning of "making"or "ordering"somebody to do something.

我令你失望了，令你失落了吗？为什么你不再爱我了？

Did I disappoint you?我让你（令你）（使你）（导致你）失望了吗？or 我辜负你了吗？ Did I let you down?我让你不开心？or 我令你难过 why do you not love me any more / any longer? 为什么你不再爱我？

我令你失望了吗？我让你不高兴了吗？为什么你不爱我了呢？