At the start of her marriage with Sergei, his brother Pavel was always with them, he even went with them on their honeymoon. Many found this rather odd, but those in the close circle of the family, knew how close they were and found nothing odd about it. However, it wasn't long until rumors started running about a relationship between the beatiful Ella and Pavel. Sergei laughed it off saying there was nothing neither of them should be ashamed of. Which given all the facts, there really wasn't but, it does seem Ella was somewhat embarrassed by these rumors.
I have never heard anything about Nicholas of Greece so I could not tell you.
Ella was overall accepted and loved by all of the family. Nicholas II was very close to her and it was with her help that he managed to keep in touch with Alix.
The only ones I have known to have said anything bad or somewhat negative about her was her niece Marie.