Roommate (m/23) is infatuated with someone (f/19) he has known for a week

Ok, so, I live with my ex boyfriend/best friend and ever since we broke up he has been trying to have sex with another girl. Beforehand, all he got was some drunken oral sex, kisses and biting, and it was really depressing him, as he felt no woman found him attractive. Last Wednesday, he started talking to a girl whom he met on a dating site. She is his type; metalhead, tattoos, thin and nice breasts, and she spontaneously messages him on Friday and asks if he is free for a drink. Of course, he goes - nothing ventured, nothing gained. Now he comes back, early Saturday morning and said that yes, they had sex. Here is where it gets weird.. He said that she said she initially wanted him just for sex, but afterwards she 'Started feeling attached, and getting feelings' for him. Saturday is filled with them sexting, trading nudes and general after sex stuff. Also included are some romantic gestures and words, and they plan for her to come to our apartment next weekend. On Sunday, he then says they have 'all but declared relationship status' but have to hold back as they don't want to move too fast. The week starts with her taking over his entire life. Her photo is his background for his phone, and computer, they talk every available minute via Whatsapp, he has purchased new bedcovers for when she comes over, has told his family and friends about her (who are all supportive and find it cute), he has even made a brand new Skype (as his old one was virus infested) and has made her favourite picture of him, from three years ago and which he no longer looks like, as his profile picture as well as a romantic message. They are meeting on Thursday since he has an appointment in the town she lives, as well as her visiting on the weekend. The entire time this has been happening, I have had an intense gut instinct that this relationship, if it ever happens, will be a disaster for them both and he will be destroyed emotionally and will become impossible to be around.I cannot speak about this to him, as he is very stubborn, refuses to listen, and will most likely ignore me for a few days, as I have had this feeling before about these girls. He never listens, and I my instinct is correct regardless. My question is - What do I do? Do I talk to this girl face-to-face on the weekend like the adults we are and see what she wants from my friend, or shall I just leave them to it. Am I right to trust my intuition, or am I just being overemotional and weird?

I see your point. One reason I could not move out was, when he broke up with me, I was three months pregnant with his child. She lives with adoptive parents, as he said if I wanted to keep her I would have to move out. He told nobody except his closest friend and work colleagues. I have contact with the adoptive parents, however he has absolutely no interest in her - to the point he keeps it a secret from every girl. He is not even registered on the birth certificate as in Germany, fathers are legally required to pay child support. I feel deeply wounded by his rejection of the child, and am admittedly making live hard for him in response.

Granted I no longer live with my ex, but I would not introduce her to my new dates, at least until I am in a relationship that I feel is going to be stable. I feel like it is kind of unfair that you have to stand by and watch him date new women, and hear about how far he has gone with all of them. I actually get a little broken up inside at the thought of my ex dating someone new, and would much rather not think too much about that - only hope that if she is with someone that they are good to her. Your situation with this guy is not sounding good. I feel like you care about this guy still, at least as a friend. So much so, that you seem a little concerned about the women he is dating, and if they are good for him. And maybe you two still have a pretty open friendship and don't really mind sharing your personal details? But it seems unfair to me that you have to hear about him getting blow jobs and having sex and actually seeing and hearing about these new women. Does he hear about the new people you've dated? And how you finally got that tall, rough-in-bed guy you always wanted since you broke up? Susie is right, this doesn't seem like a healthy situation to be in. The plot only thickens with this news about how he made you give up your baby so you could still keep your house. That is enough to show me what kind of guy this is. I would be there for my baby and its mother - and I wouldn't make her get rid of the baby or give her some sort of twisted ultimatum because my feelings apparently mean more than our child and friendship. He doesn't even pay child support - what a dunce!!! The fact that he is even hiding your child from these new women, shows that he isn't being fully honest with them. I wonder if these women would still want him if they saw his true colors?

Altreal, I can understand your point about him not being completely honest with the women. Yesterday I mentioned the child in passing and he said 'Well she (the girl) is never going to find out about that'. One girl he wanted to get with WAS aware of the pregnancy, however he had previously told her that we had never dated, so she assumed the child was not his. We are quite open with each other about people we like, however this is the first time I am ever going to meet one of these intended women. The difference with this one is she is the first to ever get attached so quickly, which he also does with people he likes. He is also quite withholding with basic information about her; not something he did with the others. Whenever I ask something like 'What is her job?' he simply answers with 'Stop asking me, ask her yourself.'

UPDATE: They are now in a relationship, and hours after the fact, whilst he was still in her presence, she was trying to kill herself. Still think I should do nothing?