bf acting different

my bf has been acting different for about a month now. he rarely says anything romantic or sweet to me anymore, communication through texting is very minimal now.... he plays video games a lot which isn’t my concern but it’s just weird he doesn’t rlly ask questions about my life anymore and doesn’t really put a lot of effort in. this made me not wanna put effort in either. i’m a nursing student so i cant have this stress of worrying, esp because i’m falling in love with him (haven’t told him yet). he told me he loves me but rarely says it throughout the week, only when we see each other on weekends. in person he’s romantic and a great bf, but through the week he’s not. is he using me just for sex????? i’m seeing him tomorrow, how can i bring this up?