Stephanie realy wasn't very popular on court in Vienna. So her position was very difficult especially by this. But despide of these conditions she had quite big confidence and strong personality.
The main Reason why Archeduchess Marie Valerie disliked her and sow enemy in her, rose in her close relationship with her mother.
When She sow, that Elisabeth didn't like her and still compained about her, she shered her mother's opinion, I think.
In Marie Valerie's diary you can find a lot of examples. She considered Staphanie for cold mother and wife, and blamed her, that since their marriage, Rudolf's behaviour changed to worse.
Somewhere I read also that Archduke Karl Ludwig felt sorry for poor little Erszi, that Stephanie is so cold to her.
I don't know wheather these rumours are for 100% true. But if yes, I see no wonder in that. Because Stephanie had realy sad childhood, she had to live without love of her parents, especially father Leopold II. He is well known as a cruel bad man, horrible father and husband.
So how could Stephanie know to display love to her child? Propably from her early youth she wasn't accustomed to do it.
Her only real happiness was, that she met Elmer Lonayi, her second husband. Because neither her marriage with Rudolf, nor her early years with her family in Belgium was happy.
I read somewhere that Leopold very insisted on this marriage- only son of austrian Emperor was surely good company and Stephanie as a daughter of King of Belgium was undoubtedly very interesting and rich as a bride.
I've never heared about any her affairs during her marriage with Rudolf. But is quite likely when we remind how pitifull relationship Stephanie and Rudolf had each other.