Lev sends an email to Claire saying that he is, in fact, going to take six months of vacation, and telling her where's he's at on various projects so other people can take over. He tells the head of the Aarons Foundation that he trusts them and his employees can make any grants which seem basically reasonable as long as they aren't about psychedelic decriminalization.
He doesn't go to bed with Sasha. He opens a new document so he can think.
Evidence that Sasha is lying: it's what you'd expect to be true, if you're paying someone to be your romantic partner. Sasha has not said or done anything blatantly inconsistent with this hypothesis: you'd expect him to say that Lev makes him happy once he knew how important it was to Lev. Lev had a panic attack in front of him and has cried in front of him twice even though they haven't even known each other for two days; Sasha wanted sex (maybe?) and he had to deal with Lev panicking instead. Lev is sad and desperate and needy and all of that is unattractive.
Evidence that Sasha is not lying: He sounds sincere. Wishful thinking.
He drafts an email to his broker telling him to put ten million dollars in an account in Sasha's name. He deletes it.
If he gives Sasha ten million dollars, he'll know for sure. But then Sasha will leave.
He's not... doing harm to Sasha, he doesn't think. Sasha prefers what they're doing to his other available options. He might like it better if Lev gave him ten million dollars and fucked off, but it's not a harm to Sasha to only offer the trade he's willing to make.
Being in love with someone who doesn't love you back but is pretending to love you is going to be emotionally harrowing, Lev can feel it. But his bed feels too large and empty when he thinks about Sasha not being in it. He wants-- he wants cuddles, he wants sex, he wants a romantic vacation, he wants to watch all Sasha's favorite movies, he wants to hold him while he cries, he wants to buy someone ridiculous presents, he wants to celebrate holidays together, he wants to be able to love someone. And the thought of doing all that with someone who isn't Sasha feels like a knife in the gut.
He redrafts the email to his broker. He sends it.
Six months. He can have six months, and then he'll tell Sasha that Sasha's rich now, and then Sasha will leave, and then he'll always know what it was like to love someone.