Is Felix an idiot? He's literally obsessed with Adele.

He's not the idiot she is. She knowas that he never really experienced love and does not know how to show it and given that pressure from Adele it's normal that he is stuttering

Nope, its precisely because she knows he's never experienced love that she's doing this. Did you see that little smirk she gave when he tried to stop her from leaving? She just wants him to be aware of and come to terms with his own feeling once and for all before they get married.
(=・ω・=)