Sex scene of my new novel

I'm half way through writing my most recent novel and I've hit a snag. Considering all my friends think I'm a sex addict and I've been named as a 'sex writer' on several occasions it's the sex scene I've gotten stuck on. The first time my characters go to bed with each other is a tricky business, and so many books get it wrong, it needs to be right, sex but realistic, hot and make you want more but not giving so much detail that it becomes disgusting. It's very tricky. For now I've left a gap with red font reading : Add in sex bit and then I've continued with the rest but its nagging at me. It needs to be right and for once in that department, I'm not feeling inspired.