A sad but very real letter. Unfortunately some parents are unable to compromise or find the right balance and ultimately when the child reaches a certain age they come to regret their earlier decisions.
However………
We must respect that the parents think they are doing their very best for their child. We do not know the ins and outs of this story. Many Litvishe families won’t take someone from a Chassidishe family as they feel if they are interested, there must be something wrong! and vice versa, only to retract that thinking years down the line.
The Hashkofo and way of way of life differences between Chassidish and Litvishe families is enormous so we need to bear this in mind, as well.
If a Rov became involved to speak to the parents then maybe they would start to see clearer but well meaning souls butting in, is I am afraid not the answer, and will act as a red rag before a bull.