I frankly don't think it matters whether or not he is going to do it again (even though it is very likely he will); The fact that he lied in the first place says something very fundamental about him and his perception of you: He lied to you so that you would agree to something you would not have agreed to, otherwise. He manipulated you and deprived you of your BASIC right to make informed decisions. THAT is what is wrong about lying when there isn't something incredibly important on the line: it is disrespectful and treats you in ways you would not or should not agree to be treated. Furthermore, the fact that he did this after you had made yourself emotionally vulnerable to him in the context of a relationship-- no! SO THAT you would make yourself emotionally vulnerable to him-- is despicable. Lying in relationships when there is agency and emotions on the line is disgusting to me, i don't care what form the relationship takes.

IF YOU DON'T THINK SOMETHING IS A BIG DEAL, THEN YOU SHOULD NOT FEEL INCLINED TO LIE ABOUT IT.

DUMP HIS ASS.