Could it really be... love?
Someone might say that sex is not a good time to decide about love. Oxytocin and all that. Yes, it is, but it is also a feeling of complete trust, which is not bestowed on everyone, and he, in relation to Gustav, had no doubts at all.
Gustav would never hurt him. Ever. It was as David's father had said. Gustav would sooner hurt himself than someone else. It was beautiful, but scary in its own way. The thought that someone could care so much about you that they would squander even their own well-being....
And David? Didn't he hurt Gustav by being with him without being sure it was love?
Wasn't he hurting him by considering, even for a second, that he would take money to leave him?
And Gustav with all the power of his breathing, with all the strength of his beating heart caressed him taking care not to go too far in a fit of passion and do him any harm, albeit quite accidentally.