I second Sexual's motion, and would like to add that if you wanna go anywhere in your dating life and be hapyy with it, then you need to learn how to not care what other people think about you. It doesn't matter.
Also, you need to keep yourself from creating negative assumptions about what people are doing, thinking about what would they be doing. that doesn't matter at all. None of this "I bet they're talkin' behind my back about me" stuff.
Well, the thing is buddy, regardless of these two chicks, you've got deeper issues that you need to get in touch with and solve. I can already see it coming that you're probably not gonna end up with either of them. If you take any piece of advice away from this website, it should be do not mess with women that have boyfriends. DO NOT DO IT. Why do you even want to involve yourself in that drama? You are actually stooping to the level of trying to manipulate her to dump this other guy (and possibly piss of one bad mother of a dude in the process) so you can "date" her with the eventual goal of doin some hardcore bump n' grind. You can try to deny it, but that is truly what is taking place in the situation with #1. Girls that already have boyfriends cause drama, Don Juans don't put up with drama like that.
With Girls #2, You've already failed because you already don't believe you can get her. Even besides the fact that you don't believe you can, you are already thinking about the end game of getting her pants off. You haven't even gone on a date with her, yet you already know you don't wanna have a relationship with this girl at all? There are alot of things wrong with this situation here that I'm to sleepy to go in to.
Gimme a break, it's 2:15 in the morning here.
Seriously though dude, you need to get your inner game in check before your outer game even begins to make any sort of difference. You should read the Book of Pook. It's on the internet, just goggle that sh*t. Read through the ENTIRE THING. don't make any excuses about this man. You need to do this for yourself. It wil open up your mind to whole new possibilities my friend. If you get you inner game in check, everything else falls in to place. I mean if you don't know how to ride a motorcyle, are you just gonna hop on a super bike and try to ride that motherf***er off a ramp? You're gonna fail badly. Same thing goes with learning how to get women. When you don't really know how to get it done, then how do you expect to be able to get any girl? And learning how to get it done comes from getting your inner game solved first. trust me on this one buddy. It will change your whole f***in' life