Satoru knew. He knew you're in a relationship and he couldn't even imagine doing it to his partner if he ever had one. To you it's different.
He's so deeply, madly, devoted and in love to you that he tolerates you for it, plus he's also taking a benefit from it. He has you too, that's all that he needs.
You're in a 3 years relationship but you knew there is no spark anymore, everyday is just a cycle and your partner started just treating you as his maid in his house.
You felt like the relationship is choking you, so you resort into finding comfort in Satoru's presence. Just like tonight, you're in Satoru's place, all you knew is it's a bad night.
"Why don't you just leave him, and... be with me"
Satoru spoke as he broke the silence between the two of you, arms still around your shoulder for comfort while you guys lay on the bed, just cuddling after an intimate moment.
"Maybe it'll be easier for the both of you? And me" He chuckled lightly heartedly.