Your question: "How good and true and reliable is Google Translate for turning English into Chinese (simplified) when talking about sensitive subjects, relationships, communication issues etc.?"
Chinese and English are extremely different. Good, true, reliable? Electronic translation still has a ton of room for improvement, especially when it comes to "sensitive subjects". I'd say any electronic translator is practically useless for what you've described. Google is probably the best, but MS Bing is almost as good, so you might as well use it for a second opinion. Baidu translation is probably even worse.
Why not try a little experiment? Translate something to Chinese with Google, and back to English with Bing.….