It was my last day in Germany, it was night and i was going back from a club to my hostel.
My friend who was also with me on the trip was talking to a girl and he seemed to fail.
Then while walking i noticed 3 cute girls walking besides me, a hb8, hb7 and another hb7.
They looked like they were 27 or 28, i don't know because i never asked (i'm 22 btw).

I wanted to initiate a conversation and decided to ask them directions to a club i wasn't going to.

*I approached the hb8*
After getting just a few words out, her friend, one of the hb7 took a few steps and kind of pushed the hb8 aside and started talking to me.
She was also cute so i didn't mind talking to her.

hb7: follow us, we're going to a pub near that club.
me: hmm, ok.

*we started talking*
What i got from her is that she's from Berlin, her name which i forgot and some other details.
Then she took my hand and we held hands fingers intertwined.

*We went on and off the train, the other hb7 went back home and we continued walking*
hb7: blablabla
me: blablabla
hb7 to her friend hb8: blablabla in German.
me: *shit i wish i knew German*
as we walked she kept getting closer and closer to me until our bodies touched, it seemed like she was going kino on me.
Occasionally she would also hold her friend's hand (no idea what that meant, maybe you can tell me).

As we walked some guy looked at me funny, the hb7 then said "he was looking at your ass", I said "i know, it's irresistible".

I wasn't talking much and was constantly thinking on whether i should be going with them to the pub or not. I knew the hb7 wouldn't come with me because she was with her friend and besides i didn't know what to say to make her want that.

Then i started thinking about my friend who was also going back to our hostel but didn't have a key (we had only 1 key and i was carrying it).

Eventually we reached their pub, i said goodbye and kissed them both on the cheek and went back to my hostel where i found my friend sitting on the floor.

I'm still not sure whether or not the hb7 was really into me or she was just being really nice. I also think i did a big mistake by going back, because my friend could just ask the for another key (the owner of the hostel was also sleeping there, so he could wake her up. A bit embarrassing but he would've survived).

It would be great if you can give me some tips on what i did wrong (i guess that i did more wrong than good).

You did nothing wrong except start worrying and psyching yourself out.

It's kinda good what you have going on. Women feel comfortable with you because you are not showing the want for advancement. She said that someone was checking out your ass. She was basically giving you a complement and telling you that she likes you physically. She started touching you so if you would have stayed with her kept your cool and had fun; I don't think you would have needed to game her. Because by not displaying need she had the comfort to express her urges. She was getting pumped up to go dance or party or what ever. She was also on another level signaling her "buying temperature" and willingness to sleep with you. You should have stayed and kept it cool, passed the shit tests ect. but I don't think I would have ditched my buddy either.

You could have got her number by saying: "Look you're drunk, I'm not. I'm not that type of guy. Plus I have to go see a friend. Give me your number and..." You can fill in the rest. It's best to come up with a reason. Especially one that will not be questioned and flow naturally. The more direct, the higher risk but also the more reward. "...we'll talk" or "I'll take you out" work. It's not really what you say but acting as though in your social circle and your reality, what you are doing is normal. And her agreeing is what you are expecting to naturally occur because in your reality it always works. She will only question the moment if you get stifled questioning yourself.

The moment you beginning to worry, you need to change your state to excitement. Use that fear to be the "flame" so to speak. It's like harnessing your natural masculinity.