Santiago Cordero pounced and dived over to win the game for the French side after Matthieu Jalibert's penalty rebounded off the left post.
BT Sport pundit Ben Kay claimed during commentary that Henry Taylor should have got to the ball first, while fans on social media felt there were a few Saints players who could have beaten Cordero to the punch.
But Boyd said: "When you get a freak situation like that, a leg-spinner off the post and it hits the ground, it's hard to blame somebody for that.
"I don't think it's got anything to do with confidence when the ball hits the post, spins one way and goes back the other way.
"You'd be hard pressed to say it was a confident or not confident side that would deal with that.
"Sometimes when things don't go your way, they don't go your way. It's nothing to do with confidence.
"You've just got to get past those things and we had enough territory and possession to win that game.
"We were just inaccurate at times when we needed those things to stick to give us some margin.
"As we've seen in the Eight Nations and with the way teams are playing the game at the moment, tries are more difficult to come by and if we were going to point the finger at anything it's that we should have scored when we put ourselves in the position to score three or four of them."
Saints have now lost 11 successive matches in all competitions, and 16 of their past 18 in total.
And Boyd added: "We're finding new ways to lose games of football.
"We shouldn't have been in that situation.
"We had more than enough opportunities to put that game past seven points.
"We know what we need to do, we're just not doing it.
"I don't think we lack confidence, we just lack constant execution.
"Nothing's going to change for us. We've just got to keep working."