<human>: I'm M23, she's F22, dating 9 months.  Like the title says, she talks to this dude fairly often.  She openly chats with him about non romantic stuff like her cat and music and stuff through text and facebook chat.  She openly talks to me about how much she was in love with him years ago in high school and that he passive aggressively rejected her at that time.  The subject of marriage came up about a month ago and I gave my thoughts: not until at the earliest my late twenties at the earliest until I *know* for certain no one else can be my significant other in a better way.  Her response "Well I just thought M and I would get married and live in Portland forever" ... This was the only time out of multiple where I made my stance clear, I basically said to her "You know this guy never liked you romantically? I don't care about him and I don't want to hear about him."  She looked like she got uncomfortable but she definitely understood the message.  But it still hasn't stopped her from talking to him on a regular basis, they'll sit and chat for hours on facebook about once or twice a week, in addition to texting little things to each other a couple times a week.  She always seems way more excited and into talking to this guy versus anyone else, myself included.

At this point I'm starting to feel like it's disrespectful to the relationship that she's doing this, it almost seems from an outside perspective that she's pursuing this guy again.  I can't keep pretending like I don't care anymore, that worked in the beginning to boost her attraction to me because she saw me as an emotionally stable, confident man; but now it works as a key for her to let loose around this guy. 

How do I step in and say enough is enough without looking like I'm trying to control or force her into something she might not want to do?

Provide a brief overview of the text.
<bot>: GF talks to her first love too much, it's starting to bother me, how to approach her about this without her feeling controlled or offended?