^Considering how ferocious Irisa was at the start of the love scene, I don't think her expression was meant to show lack of interest. The makeup appliance might make it harder to read her expressions from some angles.
I also think there's something to that look. Maybe not lack of interest but more like an introspective look. We know Irisa and Tommy didn't have the time to develop a deep relationship. In the next episode it's most probable that Tommy and Irisa won't be an item, in the sense of a full fledged couple based of love and sharing of values. We didn't see them interact that much on screen and in TV shows, we usually get much more screen time (a bit less in movie) to build a relationship until the climax moment when they first make love. It was not the case here. So the relationship seems to be based on the heat of the moment kind of thing. Maybe Tommy will have his heart broken. at least, at first, then maybe the situation will evolve beyond that or not.
Overall, an enjoyable episode. While it's not yet a series for the ages, it is part of my TV shows rotation.