Why was Jane so invested in the ingrams?

I think your quesstion is embodied in the character of Blanche Ingram. The young and beautiful society lady who is Jane's primary romantic rival. Jane is convinced that the haughty Miss Ingram would be a poor match for Mr. Rochester, but she believes that Mr. Rochester prefers Blanche's beautiful appearance to her own plainness. Mr. Rochester is aware that Blanche is only interested in him for his money, but he pretends that he loves her in order to make Jane jealous. Blanche's comments about governesses during her visit to Thornfield are particularly upsetting to Jane and demonstrate the popular beliefs about governesses during Charlotte Bronte's time.