I'm (f34) in an ethically non-monogamous marriage with my husband (m35). I have been in an on-and-off casual relationship with a married man (m28) for over one year. Please, be mindful that I seek casual relationships only. I'm not looking for anything serious and he was aware of it. Recently I noticed that he started catching feelings for me and he started having this weird fantasies of us being in a serious relationship. This made me feel uncomfortable so I took a 3 weeks break from this relationship. I explained that I dont want anything serious but after coming back he is started talking about it again

I'm sad because I have a feeling that most likely I will have to end it to avoid drama. What else can I do?