The moment he held onto her body, Serena's eyes changed for a moment once again. He could feel that she didn't wish to act this way. Asmodeus caused her to become this way due to his selfish and irresponsible behaviour.
'I will not let you fall into madness.'
'Give me this one chance, to save you from the darkness.'
Serena was a goddess who lost everything even after trying to rebuild herself several times. The gods above easily destroyed and took everything away from her.
Asmodeus understood that his touching Yumiko was something symbolic and caused her already fractured heart to shatter once again.
That's why he became desperate, his divine power not enough to take her head to head—instead, he used it sneakily so she would never resist.
—How can I trust you when you have already done that?
—I waited so long until you could withstand me, and then you chose another!