Sex life HELP!

Any tips or advice would be greatly appreciated!

My SO and I have noticed our sex life is beginning to get a bit boring. I myself struggle at times with my sex drive, just not having an interest (tips?)... not that I don't want to or I don't love him, I do.

I'm horrible at starting sex. I just don't know how to be sexy, it always goes so wrong.

He's constantly asking me "why don't we have sex anymore" and I don't even know how to answer that?

He's accusing me of cheating, asking if I'm getting it some where else.

I don't know what to do, I really need some advice ladies