Venus was so jealous of Psyche because she was so young and beautiful. Many people would admire her all the time and she was a mortal. Most of Venus's shrines were left to fall apart and all dirty and abandoned because people were so busy worrying about Psyche. It makes sense in a way for her to be jealous because she was the person who is supposed to be admired the most of all and instead it was a mortal.
I think that it is okay that Psyche got help completing her tasks since there was no stipulation an whether or not she could obtain help. She didn't ask for the help either, just was given pity. Venus didn't specify if Psyche could get help at all. She could not have completed a single one of the tasks alone because they were impossible for a mortal to complete solely.