Instead of going upstairs, Damon went to the garden.
This was the day when Talia recognized him as her mate, and even though he was eager to hold her in his embrace, Damon didn't want external factors to spoil their time together.
He wanted to calm down before joining Talia and shake off the bitter taste that his interaction with Lisa left behind.
It's not that Damon cared much about Lisa, but Stephanie was a different thing.
If it's up to Damon, he would send Lisa to do some hard work in a place no one will recognize her, as a lesson to learn some humility, but out of respect for Stephanie, he couldn't do that.
Stephanie was one of the few people who stood by his parents, and who supported him wholeheartedly after they were gone without succumbing to power-hungry madness. Out of gratitude for Stephanie's years of service, Damon hoped that Lisa will snap to her senses and that Damon won't need to resort to drastic measures.