If you catch him looking at you and he immediatly looks away. A lot. This is true for both sexes.
A lot of the time, avoiding eye contact can mean disinterest. That's the trouble with a lot of shy, timid people... It's hard to know what they're up to. Often someones timidity will be interpreted as disinterest or even aloofness. I know some people who were thought to be full of themselves were actually just shy.
This:
Ok, but what about when guys stop talking to you (finish their conversation) and then hold your gaze for a few seconds (more of a direct glance than a sideways one) - is this the same thing? Is this a good sign? Lol!
is dead givaway that you're both interested. I don't think words even matter in that kind of look. Last time I held that kind of gaze, I asked her a question and her response was almost gibberish, lol

It wasn't easy for me to force out the words either.
As a rule, the more someone wants to be around you, the more they like you... and if you suspect someone likes you romantically, you're probably right (beware wishful thinking).
This:
lets you talk without losing interest (maintains eye contact) looking at his watch, turning around, and/or looking past you. doesn't read a book while you're talking (had to work on my husband after 15 years. i would raid his bag and take out books before we went to a restaurant. or, look all hurt - and tell him i refused to eat out with him again).
I've given some thought... I think that it takes some real effort to feign interest. The ladies can really put a guy through a lot of babble that we don't care about, and I suspect that a lot of the time a guy might just be courtious enough to maintain eye contact until the monologue is over. So a thought for the ladies: if you're doing 80% of the talking, there's a good chance you're boring the hell out of your victim

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