What this one is referring to is known as "NRE" - New Relationship Energy. That's when you're all doped up on brain chemicals while being both nervous and excited to see someone again. For some people, it's very euphoric. It wears off after a few months. I would assume that the purpose of this, if any, would be to bind people together long enough that they can become comfortable and familiar to each other, paving the way for a potentially real relationship.
When it wears off, that's when you figure out whether it's really love or just infatuation, and if it is love, whether it can withstand the differences between you.
NRE can be intense, even addictive to some, but the long-term rewards for finding a partner as opposed to a temporary fling are more subtle yet more satisfying for most people. Though I'm not going to judge those who prefer temporary flings, so long as they're reasonably open about it.
Every incel which I have seen has, to varying degrees, demonstrated that they have neither the necessary social skills to enter a relationship, nor a mindset conductive to acknowledging or dealing with their partners needs once they're in one. Until they do, "temporary effects of brain chemistry" is the best they can possibly hope for. Given their very poor grasp of how other people function, of course some of them are going to think anything more is a lie.
Though in a sense, nearly everything involving the human experience comes back to "brain chemistry". I am completely aware of this, including a general idea of how it all works... and it doesn't bother me the slightest. I see beauty in being a highly complex, self-assembling pattern of matter and energy, not despair.
