Is he cheating?

Rebecca
My boyfriend has cheated (on an ex) in the past and says he has 'intrusive' thoughts about other women. They can be walking down the street and he'll imagine having sex with them or even imagine living a whole 'happy ever after!' He also has said on a Reddit post that he craves casual sex + imagines hundreds of girls lining up one after another 'having a go'😳😰 
He has hidden our relationship on Facebook before and is very clever and untagging himself from things or not even allowing things on there too. Do you think he could be cheating (even just emotional cheating / messaging/video chatting people) or do you think he could do?