Somewhere on these forums somebody pointed out that for them, feeling equals fact. If he wants to have kids with you in that moment, then he states it as a fact. If he changes his mind ten minutes later, than the facts change. That has been the most difficult thing for me navigate. How can he say one thing one minute and then say or do the total opposite ten minutes later? It is rough.
Learning to deal with the idea that a stated "fact" is indeed not actually a lie but merely a transient fact, that may not stay true is difficult to accept, but you need to. It is easier to think of then am as delusional or misguided rather than outright lying.
Learning not to make many important decisions on these "facts", but likewise you also have to stop being eternally suspicious, and just take everything as interesting otherwise you drive yourself nuts