Disclaimer: I hate Farlon as a character and as a unit as much as you do but I do have a slight understanding of how it feels to sink into depression and anger so I decided to post this.

As a unit: There's no changing this at all. He's terrible.

As a character: View the scene in which Farlon accidentally takes Ramna's life in a different light.

It is generally accepted/shown that Ramna says something to Farlon before she dies. In my point-of-view, what Ramna says to Farlon, along with the fact that he kills the woman he loves, is what drives him to madness.

For me, the last words of Ramna to Farlon were:

"I decided to follow him... for the future of our child..."

For reference, below are the lores of Farlon and Ramna's 7s and I suppose it's up to you if you will view Farlon in a somewhat better light after this.

Ramna 7*:

The last thing she wished for was happiness for her beloved. However, she understood that tragedy that would occur soon. Even so, there was nothing else she could do except to wish. Her strong feelings made a miracle occur after it all ended. The flames sprouting from her body enveloped all that was left over in the battlefield. According to records left behind by a certain person, the ending of that fight was so written. "That gentle flames purified all the souls."

Farlon 7*:

To Farlon, having killed the woman he loved, her last words did not get to him. His shaking blade, now with nowhere to go, drove itself into the girl who laughed at his despair. He continued to attack his former comrades with a power that was different from before. It was said to be an intense power, lacking hesitation and arrogance. Legends say that just before he stood off with Grybe after cutting down Signas and Rina, the image of the woman she loved was reflected in his eyes.

Anyway, that's it. Everything else is up to your interpretation and whatnot.

Just to clear up: this is only headcanon and not canon... which, in the end, means that Farlon is still a jerk.