Realist VS. Pessimist

Realism VS. Pessimism... I'm not sure what I am characterized as. Let me explain...
A friend of mine starting dating a man she met online. Great - I have never tried online dating. I am neither for or against it. It makes zero difference to me where you meet. I have a few friends that LOVE it, and a few friends who HATE it, I am undecided.
Anyhoo.... They met, went on a date a few weeks ago, and have been completely inseparable since then. They chat/text/email all day. They spend all evenings and weekends together - totally inseparable. Now, he does have a job where he travels a lot. He's here for a few weeks - lots of free time - then is gone for a few weeks - working constantly. So I understand the fact that they want to get to know each other before he leaves again.
She is totally infatuated with him. Talks about him all the time, tells me all the sweet things he does - totally in lust.
Now me.... whenever she tells me a sweet thing he does - I say "awwww, that's so sweet!" and then think - "that won't last" or "he's totally playing her". Why can't I just accept that he may be a nice guy and wants to spend time with her and do sweet things.
They seriously spend every living second together - and I WANT to tell her to take it easy, don't get too attached too fast.... but why? Maybe he's a really great guy! Maybe he wants to be with her all the time!
Pessimist?
Bitter maybe?
Untrusting?
I don't really think I'm untrusting. When I speak to my husband and he tells me something - I believe him. I trust him. I don't think awful things about him. I don't think he's an awesome dream guy either though - of course I know him quite well - and he never pretends to be perfect. I just think this guy is a little too attentive and sweet and perfect... a little too good to be true.
I am very good at keeping my mouth shut and tell her she's so lucky and he's a great guy... but deep down - I think this guy is a bit of a player?

Dating...

Ahhhh dating.

You know what amazes me? Women (or men) that can have their husband (or wife) leave one weekend, and be dating the next weekend. Or even more shocking, women (or men) who date while they are still married, and then leave their spouse for the other person, and continue to date and live happily ever after (maybe).

Can I tell you, I have ZERO interest in dating. Like seriously, zero. In the past, having a flirty funny conversation with a cute doctor was fun. Now, it vomit inducing. Seriously, I throw up a little bit each time. I hate it. I would rather SLOWLY be ripped apart limb by limb by a dull toothed great white that's not that hungry.

Crazy hey? I actually backed away from the computer a little bit when that picture came up. How far down does his throat actually go? Anyway, dating, yah, no thank you!

And really, at this point, when you are left for no real reason, how can you ever be comfortable again. I'm 33, so I have to eventually start dating again, I can't be alone forever, but how do you not wake up every morning thinking "is this it? is this the day he decides he doesn't want to be with me anymore?" Do you ever get over that? Or is it forever in the back of your mind? I guess we'll find out!