I think a lot of those "signs" are not necessarily signs at all, especially in long term relationships.
Once you've been with someone 5, 10, 15 years, you naturally go thru ebb and flow times in the relationship. If I was ready to toss in the towel every time one of us in my relationship started spending more time online or was less interested in sex or not in the mood to kiss, we'd never have made it this far. heh.
Really, really long relationships often go thru periods where the two can barely stand each other. Sometimes, they still prevail, the ebb begins to flow again and the relationship lasts another 20 years.
In a new relationship, though? Yeah, I'd say things like not wanting to have physical contact with the person - kissing, hugging, snuggling, having sex - or not wanting to see them, choosing to see friends or work over seeing your partner, etc, are probably pretty good signs.
I just hate to see relationships tossed away too easily based on signs that don't always mean it's over, that sometimes just mean you're human and need a break.