I'm going to cancel an interview on the company's dime
Why do you want to cancel?
I think my boyfriend is cheating on me and I don't want him to spend all of my money on some other lady while I am busy with this interview
It is wrong to waste your company's money on personal matters.  If you are having problems that you need to attend to, this should be done on your own time, or with some of your own time off.
Why should I care? This isn't my company, to hell with them. I'll make sure that I'll post this online too.
Your behavior just seems really unprofessional, especially based on some hunch. I think you should go through with the interview and handle your personal matter afterwards.