what should i do ?

i’m in relationship with my fiancée for 6 years, but he most of the time acts like we have been married for 50 years. He doesn’t talk to me that much, he seems most of the time nervous if i wanna talk with him. We live together, but for the past half the year it’s like i live alone...what should i do? i love him but i don’t understand why he’s like that. He said it’s nothing and gets angry and sometimes louder bc i say to him that i feel unloved and alone .

( no, he’s not cheating i’m sure of it i look up very good) he says he loves me but i don’t feel him close to me like before.