Douter: to doubt, to have doubts.
Douter de + noun or pronoun, douter que + clause
To doubt: je doute qu’il vienne (subjunctive mood because there is a doubt): I doubt he is coming
Not to be sure: Il m’a dit qu’elle n’est pas là, mais j’en doute (listen to the video about the word “en”): he told me she is not there, but I am not sure.
Tu me fais douter: you make me doubt myself
Douter de: je doute de lui: I doubt him (to mistrust)
Se douter: to suspect, to guess.
Se douter de, se douter que
To suspect: Je me doute qu’il va venir (indicative mood because there is no doubt): I suspect he will come
Je m’en doutais: I suspected as much, I knew it.
j’aurais du m’en douter: I should have suspected that
J’étais loin de me douter qu’il allait venir: I did not have the least idea that he would come