Wan-Bissaka's late own goal contributed to England losing its opening group game 2-1 against France and Boothroyd feels the defender has been affected by talk he could be moving to Old Trafford.
The Eagles have made it clear how important the 21-year-old is to their plans, with the youngster flourishing in his first season in the Premier League last term.
Manchester United have failed with a £50m bid for Crystal Palace defender Aaron Wan-Bissaka, according to Sky Sports News reporter Kaveh Solhekol.
The Crystal Palace full-back is now away with the England U21 side at this summer's European Championships in Italy, with the 21-year-old reportedly having agreed personal terms with United, who have so far seen two bids rejected by Roy Hodgson's side.
However, similarly with Wan-Bissaka, United are not the sole team interested in Hysaj.
Williamson guides Black Caps to win over South Africa
A hard match was lined up for them against India on Thursday at Trent Bridge but the match was abandoned due to rain. In the match reduced to 43 overs per side, New Zealand beat the Proteas by 4 wickets with one ball remaining.
The report further adds that the fee agreed is, in fact, around £60 million, and the aforementioned meeting will be used to iron out the finer details of the transfer.
Capturing the starlet also fits in with the approach manager Ole Gunnar Solskjaer appears to be taking with regards to rebuilding and reshaping his stuttering United team.
Wan-Bissaka enjoyed an outstanding campaign at boyhood club Palace in 2018-19 making 39 appearances in all competitions. This has been going on a long time.
"When that speculation is flying around it's bound to turn your head", Boothroyd said.
"I thought it was going to be the other way round because I thought Wilf would go and we'd keep Bissaka".