if black play c4, then after f4, isn't the c4 pawn now hanging ? ;)
Sorry, I had it on worng move. 15. ...c4 establishes the pawn chain from a6 to c4. This gives me a horrible LSB and establishes a serious Queenside majority attack as well. At that point, Bh4+ takes advantage of my pawn structure and I think I can even lose the positioni here. If you have an engine, input 15. ... c4 and tell me how it plays for White as well.
moves 27-29 were the deciding factor in this game.
POSTSCRIPT: Had Black played 16. ... c4, he could have had a superior position.
Your opponent blundered a pawn, rook, and knight. All in a row.
Only a fool would NOT resign after a triple blunder. Apparently he was.