There is no point in doing it. Save her the pain if you do. If you aren’t happy with her, then don’t bother going for another girl just because you don’t want her to be so much in pain. She will be so much in pain when she finds out. If you aren’t happy with someone, just end it. Save the excuses, because you know she deserves better. No one deserves to be cheated on, so don’t do it.