There were flurries when Boro looked dangerous, but they were too infrequent and apart from a couple of corners they amounted to little.
As they did the first, Bournemouth started the second half brightly and Konstantopoulos was called into action in the opening minute as he dealt with a difficult free-kick from Matt Ritchie and header from Tommy Elphick.
There was little Konstantopoulos could do as Bournemouth increased their lead on 48 minutes when Harry Arter from outside the box found the top corner with a left-footed shot.
Aitor Karanka made a double change with just nine minutes of the second half played when Nsue and Adam Clayton were replaced by Adam Forshaw and Kike.
Shortly after a fine cross from Adomah was turned behind for a corner, Bournemouth should have gone three up but Matt Ritchie cleared the bar by some distance with the goal at his mercy.
Boro had the ball in net when Kike headed in a deep cross from the right, but as soon as the ball was delivered the linesman’s flag was raised for offside.
Referee Anthony Taylor made a big call on 74 minutes and he called it incorrectly. Arter fell when challenged by Leadbitter with no contact.
Mr Taylor could have shown Arter his second yellow, instead he pointed to the penalty spot and Brett Pitman comprehensively beat Konstantopoulos.
Patrick Bamford went close with a free-kick in the closing stages when a 22-yard effort appeared to wrong foot Artur Boruc and skim off the top of the net.
Despite the fact team failed to muster a single shot on target and they conceded three for the first time away under Karanka, Boro’s fans were defiant at the end, loudly applauding the team who returned the applause in acknowledgement of the commitment.
Scorers Kermorgant 12 (pen), Arter 48, Pitman 74 (pen).
Bournemouth: Boruc; Francis, Cook, Elphick (Capt.), Daniels, Surman, Pugh (Off injured on 90+2), Arter, Ritchie (Smith, 65), Kermorgant (Pitman 60), Wilson (Rantie 90). Subs: Camp (gk); Ward, MacDonald, Fraser.
Middlesbrough: Konstantopoulos; Nsue (Forshaw 54), Kalas, Gibson, Friend, Adomah, Leadbitter (Capt. to 78) (Whitehead 78 (Capt. from 78), Clayton (Kike 54), Tomlin, Reach, Bamford. Subs: Ripley (gk); Omeruo, Wildschut, Vossen. Order of subs on 54: 1) Forshaw 2) Kike.
Referee Anthony Taylor
Bournemouth Arter 57, foul
Middlesbrough Clayton 36, foul; Nsue 43, foul.