...surely I am with you always, to the very end of the age.-Jesus, in Matthew 28:20
Jesus doesn't waste words. If he only had to say "surely I am with you always," he would have. For some reason, he chose to add "to the very end of the age."
Jesus always includes our imperfection in his plan for us. He knew that in times of trial we would start to doubt him in our hearts; he had even seen it many times with the disciples. This is such a universal tendency (yes, you're not the only one) that a second assurance was necessary; he's with us no matter what, right up to the moment of the rapture.
It's not about whether we feel like he's with us or not; he always is. Do you think David "felt" like God was with him when he was hiding in the field waiting for Jonathan to tell him whether he had to leave for good or not? But God was still there, the whole time.
Remember that fact and act on it. Don't give in to the despair of your circumstances.