1. You don't trust them.
This presumes that you did trust them at some point; if you're in a relationship with a person whom you've never trusted, something is wrong with you! If you did start out trusting them but now watch their every move (particularly when they're not looking) then not only is your relationship on the way downhill, but you're also a stalker!
2. You'd rather work.
Are you one of the countless people who works 16 hour days because you'd rather slave away at the office than go home to your nagging wife or jerk-of-a-husband? Guess what; that's not normal. If you hate being around your partner or spouse that much, this is a good sign that the relationship is over.
3. You've separated.
If things have gotten so unbearable that one of you wants to move out, this is a sign that your romance has come to an end. Yes, in some cases, people work through issues and get back together -- but most of the time they don't. Separation is a form of breaking-up; why not just get it over with? It's amazing how people will drag the painful parts out as long as they possibly can.
4. You find your lover as attractive as you would a sibling.
This statement presupposes that you're not attracted to your own siblings, but I think it's probably a safe assumption (unless you happen to live in the Deep South). While it's certainly true that some couples are too tired or worn-out to have an active love life, if you don't actually want to engage in any type of intimacy, something is wrong. You're supposed to be physically attracted to your romantic partners -- if you don't want to get down with the person you're involved with, it's either time to get the passion going again, or time to put them in the friends category.
5. One of you routinely threatens to leave.
Granted, the person doing this could simply need far more attention than normal people, but if someone is threatening to leave, this means the idea has entered their mind and stayed there for a significant period of time. Some might be fishing for their partner to beg them to stay, but even if that's the case, there's nothing much romantic about that, is there?
