Why dosnt he want sex?

I love my boyfriend to pieces but lately he's only having sex when we drink and its him that wants it anytime I ask or start sex he says no
I know not all time people want sex but it's got its bearly happening and its making me wonder why
I honstley feel he needs drink to go near me and I feel so down and upset
I won't even try to start sex now because all he does is reject me
We used flirt mess about with eachother and kiss during day now nothing happens we give eachother a peck before bed
he's even started not going to bed at the same time as me and I feel its ro avoid sex happening
I love him so much and just want the spark back
I need attention from him and want to give him attention

How can I ho about fixing this without him getting offended
Anyone else been in similar situation
Why dosnt he want sex?
Post Opinion