feeling neglected lately

hey there i am in a long term relationship and we have been going strong for years but recently he hasnt been as interested in sex or me it feels like hes drifting away im not sure if its bc of work stress or something else but its killing me inside ive tried talking to him but all he says is that everything is fine. i feel so alone even though were together should i try and talk to someone about this or what do you guys think?