The Stresses and Strains of Sharing a Bed

Fair enough, this isn't so much a rant as a general observation on an area that can potentially lead to so many problems it is ridiculous. Scenario 1- friend comes round to visit you, between you a bottle of wine disappears, friend can't drive home, friend needs somewhere to sleep. No spare bedding and all that, so friend hops into bed with you. Two females? That's fine. But as soon as is a guy, there are problems. Scenario 1A - guy is somebody's boyfriend. If their girlfriend finds out about sharing bed, even if you both passed out through alcohol and snored in entirely seperate slumbers for the night, you are both in trouble. Scenario 1B - guy is single. Guy therefore thinks he stands a chance with you, due to presence of contents of bottle of wine inside him, and you therefore spend entire night panicking that he'll make some sort of move.
Scenario 1B can of course be broken down further - I mean, if you are single then it isn't such a bad deal (provided the guy is not total munter). But if you have boyfriend, then spend entire night panicking about any contact being made. Not that I have a boyfriend as such - treading in dangerous water here so will escape - but I did recently pass a night wide awake, didn't get a wink of sleep, because was terrified would either a, have unwelcome contact made by guy who was in my bed or b, I would wake up in night and think 'oh, that is _____' and turn over, pulling them to me. Therefore ended up in foul mood due to tiredness and absolutely shattered when said non-boyfriend-guy arrived the next night, thus arousing suspicions and generally being too tired to care who was in my bed anyway.
Am heading to London in a week and will be staying with a guy for two days who in the past has found excuse to approach me, and no, I'm not interested. Exchange of emails implies my sleeping there will require my being in same bed. I am already sweating gallons and panicking about this, and the thought is passing through my mind to spend a small fortune on a hotel room for myself instead.
I guess it all comes down to trust, doesn't it. Ah, that glorious bond which ties the dodgiest of relationships together. It is SO HARD to have to erase all the times that mean you don't trust one particular guy and not transfer them to a new guy; in fact, I just can't. I'm useless at it. And in all honesty, dear reader, I'm slightly concerned this could mean I end up losing someone before anything has really gotten started. Sigh. Let's all just get single beds and be done with it.