Why is it some guys flirt even when in a relationship?

[19magic]

I have somewhat of a crush on this guy who works in a store near where I work. It's the closest one to my job and also the cheapest one, so I go in there often to pick up a few bits and bobs and sometimes to do a weekly shop.

But every time I go there he also tends to be working and he's always pretty flirty and sweet and we share words while at the till. Today I went there to grab a few things, and despite me going to a different till he turned around several times said hi, then made a jokey comment, then said there's the smile I love seeing.

And it's super sweet... but he's dating another girl. And while I won't lie and say I don't enjoy it, I'd rather receive comments like that from an available guy. Plus if he's like that with me, just how many other girls does he say things like that too, and yes he's aware of my attraction to him.

But if you're in a relationship why act like that, I don't understand it? Is it a guy thing at all?

Updates

8 mo

Other things he's said is hi beautiful, gorgeous, you look stunning in that. Whenever I see you, you brighten up my day. The first time we flirted he told me he has a girlfriend, since then he's also said he's brought a washing machine with her. As for him knowing, I went through a stage of being super clumsy. I said, I don't know why I keep doing this, I swear it only happens around you. Maybe it's my dashing good looks then that causes you to stop and stare.

[Anonymous]

I’m not sure if he’s actually flirting w you. Maybe he just feels sad for you in a way so he tries to brighten your day by saying you have a beautiful smile. I don’t think there’s anything wrong w complimenting someone on a beautiful smile, maybe they have nice teeth. Him saying hi doesn’t constitute as flirting either. Sounds as though you’re a regular so maybe he says hi to everyone or to people who are regulars. Let’s say he was flirting w you. First of all how do you know he’s in a relationship? Second I think it’s on a man’s nature to want, or look at many other women. Even in the animal kingdom this seems to happen. Sure some species mate for life but I think it’s similar. As for flirting, well it may give him a little ego boost. Maybe he wants to prove to himself that he still has it, the looks or the skills to pick up women. Maybe he wants a chick on the side.

[spartan55]

How do you know he is aware of your attraction to him? How do you know he has a girlfriend?
You didn't give any examples of behavior I would consider flirting, so I don't really think he is 'doing' anything.

by the way, girls are every bit as guilty of this behavior.

[ohmyguy]

Woman do too...
The reason. is the fact that we are taken make us tiny bit more attractive to other woman. Our confidence peaks we are bit more bold.. our ego gets boosted.. our brain shrinks as our pens grows

[Subflics]

We don't know that he isn't just friendly or flirting. He may not act on those things. Regardless if it bothers you, maybe find another store

[bananathunder]

he could just be acting nice? People in customer service do that a lot. Especially with regulars

[DerekC321]

Some guys see a beautiful girl and they can't resist

[In_Trance]

For all the same reasons women would do it

[19magic]

I'm not saying some women don't do it too. Just that I don't understand it, if I'm in a committed relationship, I only have eyes for him and no passerby even comes close.

[In_Trance]

Maybe people aren't getting what they feel they need or deserve out of the relationship.
I'm not justifying their actions however flirting definitely does give you a dopamine release

[Anonymous]

Why does a dog lick it's balls? Because it can.

[Jojojojojojojo]

Because he wants some side chicks?

[jahaims]

Because some people cheat. Pretty obvious