Why would he keeps Ashler away from Abel? Is it because of jealousy (￣∇￣")?

yes. because abel told the king that there's a mighty knight or something (the pomegranate chapter) and the king thought it was sir ashler so now he's jealous of him

Oh no wonder (≧∀≦) with his personality I'd totally misunderstood him too ╮(￣▽￣)╭