This is going to be a long post, so here we go. I have a friend/old coworker whom I used to talk to a lot at my old job. We still talk often on Facebook but we're not close enough to hangout. She has a new boyfriend now, and she's very happy with him. She used to date a guy, who likes me now named Zach, and she told him about me. I was going through a tough time last year, in grade eleven with a brief boyfriend I had, and the old boyfriend, started bullying me, so, Zach stood up for me against him and I thought that was quite nice-- After all, I'm much too shy to have done anything myself. So that was that, and I didn't think anything of that, or Zach again.
My female coworker and Zach broke up, and he added me on Facebook, so I accepted. One night, he started posting depressing Facebook statuses, which made me quite concerned. I would take the time to talk to anyone if their upset, and I thought I could return the favour to Zach, since he stood up for me before. I asked my coworker if it was okay if I messaged him and asked if he was okay, and if I became his friend if he wanted to be. And she said yes, but she didn't want anything to do with him, but thanked me for being there. So, I messaged him and he became my friend.
I did not intend for a relationship with this boy at all, in fact, I have never truly had one with anyone. I am eighteen and I have never kissed, had intercourse or anything, nor have I smoked, done drugs, or drank etc. But, Zach really started to like me after we became friends and started texting me and messaging me everyday. He is a very nice boy at heart, but does things I don't approve of, for example, he smokes weed and drinks a bit. Sometimes, he would ask me to drink with him, and when I would say no, he would say things like "I'll keep you safe if we drink, it'll be just us..." and I would say no thanks again and he'd get snarky and say something like "Okay, just live In your innocent bubble, you don't experience anything in life."
I thought that was off-putting, and it truly bothered me that he liked me even though he was my friend/coworkers ex. So, to make sure she didn't care, I told her about when he asked to hangout and if it would bother her, and she said not at all, I could do whatever I wanted with him. So, I continued being his friend, and friend zoning him when he said he liked me. Which he did, almost everyday. I stopped feeling bad about him being involved with my friend, and got to know Zach, and he really opened up to me and appreciated me, which was nice, but I never said I liked him back or anything, because I don't know if I do. He could be controlling too, he gets very jealous if I hangout with my guy friends and calls them mean names like "Faggots." One time, he called me a bitch because I didn't text him back right away, and I got upset, and he applogized and got upset with himself for calling me that. He also got drunk one night and started messaging me telling me that "I am too cute for a virgin" and since I believe in no sex until you're married "I am a nun" and I simply "Don't want to have sex, because a guy hasn't ever treated me right, like he will." I got creeped out, and said I had to go, and after he wasn't drunk anymore, he said he meant it because its "Attractive" that I am a virgin, and he loves my "innocence" and told me he wanted to teach me to kiss and give "hickeys." He hadn't been like this before, so I stopped responding. If he wasn't sexual, or didn't drink or smoke he'd be wonderful, but when hes like that it makes me feel weird. One time, he even told me he'd stop all that if we dated, because hes never had a good girl and he wanted the best for himself and me too.
Hes also Bipolar, and that's fine to me, I really don't mind, but hes not medicated and refuses to be, even though I encouraged him many times. Maybe that's why he acts so sweet and then so creepy but I don't know much about BPD to draw that conclusion. He would say he wanted me, and I'd wouldn't flirt back, I'd just be very nice to him, so maybe that's why he started having intercourse with a girl whom is very very mean to him and one day, he texted me crying because she was being so mean. Then, he started dating her and telling me about it, even though he knew I didn't like her--for the way she treated him, or others at school. Shes honestly the meanest girl I have ever met. So, I told him nicely, in a long message that he doesn't deserve to date someone like that because he can be nice, and shes awful to him and he has to remember that no matter how much he liked her and wanted a girlfriend to feel better about himself, and that history will repeat itself, and she'll continue being mean, because that's who she is as a person. And he flipped out at me, trying to make me feel bad about myself but it didn't work lol. He called me cuss words, and saying I will never amount to anything because I'm too innocent and my mom doesn't let me do anything, and I wont survive in university, and we weren't friends anymore etc. So, I simply, stopped talking to him because he threw our friendship away because of a mean girl, and was careless with his words.
Now, I see him all the time at my new job, and he followed me on Twitter, and likes ALL my tweets and most of my selfies on instagram.......... and I don't get it............... He wasn't nice when he started dating his new girlfriend bc she isn't nice. And hes still with her, and he was mean to me, so why would he do that? I know for a fact he'll want to be friends again when she breaks up with him, but I don't know if that's a good idea anymore, because he wasn't nice. But, the thing is, hes super nice when he isn't around her. So, I don't know what to do, especially if he wants to talk again, which I feel is coming. And when hes being nice and sweet and not creepy or mean, I like him and I think hes cute, but I don't think I'd want him to be my first boyfriend, it seems like too much because hes a bit unstable, so friendship is key if anything. But maybe not talking is the best...
Thoughts?
Sometimes that wont attract only good people. There will be a lot of people attracted to you which may have good or bad intentions. Just try to observe and get to know people first before you start a friendship with them. I know its not easy since you are a good person and try to help as much as possible but its for your own good. Take time getting to know people thats my advice. 
even my own dad , who is religious said that the most important thing for men is to be satisfied sexually and they will cheat or be very sad and resentful of that need isn't met. It's really depressing but at this point I believe him.