It was nothing! Yes, thank you, I noticed and listened to the video as I was translating the song; I didn't find anything wrong with the lyrics you provided :)

In this context I'd say the meaning of "sin compasión" is closer to "without holding back" or "without showing compassion".

Example
Lo criticaron sin compasión (They criticized him without holding back/without showing compassion)
In this context I'd get that idea from "sin compasión" but it may also be translated as "They criticized him harshly/severely" and It would convey a very similar idea just using other words, yet I wouldn't use "Kiss me harshly/roughly" for the song because in that case they don't seem like synonyms to me.

I didn't use pity because it'd sound like she's feeling sorry for him to me
"Kiss me like this, without feeling sorry" is not exactly what he's trying to say but I don't know if "pity" could also be interpreted like regret or shame maybe?

Also I had always thought that the expressions "To take pity on" and "To show compassion for" may be interchangeable in certain contexts??

Please let me know your point of view, meanwhile I'll change it to without holding back.

I see!

No, thank YOU. I rarely get the chance to discuss things like these but I love it just as much as I love learning new ways of interpreting words and phrases. I never thought without showing compassion sounded like they were enemies which certainly was not the idea.

Thanks :)