Personally I always like to reverse the situation in my mind to understand it properly. So here goes.
Lets imagine your other half went out with her mates - (telling you she's at the local), actually goes clubbing in town and gets rat arsed, spends the next few hours leching at some half dressed sleazy blokes, then goes to some strange bloke's house and rolls up home in the morning by which time, you are out of your mind with worry. Surprised you've got a gf at all - sounds like you should be single to me........