Is there a difference between "I feel bad that " > "i feel bad about " > "i feel bad for " ?
Great question! There is a difference.
1)"I feel bad that I lost my cat." 2) "I feel bad about losing my cat." 3)"I feel bad for losing my cat."
Sentence #1 uses the past simple verb, "lost." Sentence #2 uses present continuous verb, "losing." Sentence #3 also uses the present continuous.
The meanings are slightly different. Sentence #1 puts the action definitely in the past, so you might have lost your cat last year. Sentence #2 implies that the cat was recently lost, and sentence #3 implies that it is your fault that you lost your cat!
And what is this sentence meaning "i feel bad that i can't talk to you " is this a result or reason?
I'm not sure what you are asking. The sentence is in the simple present. You are telling someone that because you cannot talk to him (or her), you, right now, feel bad about this fact. I'm not sure what else to say, but if you have any questions, I'll try my best to answer them. :-)