Why can't women be like men sometimes

Growing up when I was younger I would say I was more like a tomboy.  I was always outside playing with other kids in my neighborhood boys and girls.  We would play hide and seek, kick ball, tetherball, tell ghost stories, go swimming, tag.  All the activities kids would be involved in.  I was so active, I didn't think about boys.  I did have crushes since 3rd grade but I wasn't girly girl about it.  When I liked a boy my interest in him was to do what he liked to do.  We race each other, play tag, or climb a tree.  I wasn't looking at the mushy things on dressing up or kissing.  I just wasn't there yet.  So my mentality as a young child never really panned on how girls can be....catty, jealous, possessive, territorial etc.  I wasn't really into girl groups or having a click so to speak on girls dressing up, wearing certain kinds of clothes, even talk alike.  I may have a few girl friends1 or 2 besties the most that we all get along.  If I were in any certain kind of girl group it would be because my friends brought their besties and it would be then a girls night kinda thing.  But for the most part I never really had too many girlfriends to hang with.  Most of the time I had at least one guy I can kick or one guy to tag along with if I were to go on an outing with my girls.  Anyways now that I left a back drop into hanging with females it just never surprises me how a girl/woman can be sometimes, especially when it comes to men.  If  I were to hang out with my female friend and invite a guy to tag along for some reason the dynanmic would change.  My guy friend is just a guy who enjoys hanging out with the company of women.  Ok I get that.  I don't think he's looking for any type of attention or even looking to hook up.  There may be occasional flirting which happens with the opposite sex but nothing more.  We are all friends enjoying each other's company.  That's how I took it and that's how he took it so for some reason my friend had to be the center of attention and try to peek his interest some how.  Ok that's great and all but is it really necessary to be like that.  If the shoe were on the other foot and I was the third wheel and my girl happened to invite a male friend of her's whos cool, I would of been cool.  I wouldn't act weird or feel like there was any awkardnees.  It would just be a genuine good time from what I see.  But for her she had to act a fool and embarrass me in front of him.  He was even like what's up with your girl.  I didn't get it and what's worse is because she wasn't having fun she wanted to have a hissy fit and ruin the night by wanting to go home.  Keep in mind we carpooled.  It's a mess all around and I had to collect this as to why she was behaving this way.  I spoke with my male friends and it's sad and I tend to agree how females can be.  If one isn't getting attention or having fun or jealous to know someone to know someone as fine as he is she will play her insecure card by ruining it for others.  The only thing she did in my eyes is made herself look like a fool, made me look at her differently, and had my male friend question what's really up with her.  I swear this incident felt like highschool and I'm so over hanging out with females who don't have their own confidence and security.  My guy friend said this..."Men don't act like that, we're not competitive as females are when it comes to the opposite sex.  If we see a female and a guy is interested we encourage them to go for it.  Women would manipulate and back stab and compete for the next man by smiling in her face and taking him behind your back.  At least for men we may do it in front of you if there's no one's claimed, and plus we're doing our boys a favor cuz that chick was no good in the first place.  It's all about respect and it seems like females don't have that respect.  They only care for themselves. Us men we encourage each other, bring each other up and show them how to get there.  Women their all out for themselves.  Their motive is to get a man and that's her world to them."  I do see what he's saying...there may be some bitterness on his end but I understand the gist of his point.  Maybe I'm naive to the game.  But I never had that in my nature to think like that.  It's hard to make female friends like that too, who's confident in her own skin and not the insecure type who's my age.  Talking to older women is a refresher cuz the truth is they're not out there to compete.  They have that mentality like they've been there done that, don't have time attitude.   I didn't mind bringing my male and female friends together but somehow it always seems to become an awkward situation.  I guess maybe for me a lesson learned is to stop bringing my single male friends and my single female friends together, cuz woman who may be attracted to someone don't know how to act.