<human>: Can you provide a brief rundown of the text in within 3 sentences?

I am currently engaged to my [F/23] fiancé. 

While we've been together for four years and have had a lot of fun times, I feel like we aren't the people we were when we started dating and have developed different personalities (I'm social, she isn't, etc.).

I often find myself wondering what it would be like to date other women (I haven't dated anyone other than her since I've been an adult), and often find myself flirting with other women in my life (at work, social activities, etc.). In many ways, she doesn't fulfill my interests anymore.

The most difficult part about the situation is that we got engaged a month ago (I'm not entirely positive why I did it, mostly a lot of pressure from family and friends). If we broke up, I'd have a $12k ring I wouldn't know what to do with, and her parents would lose a $600 down payment they put on the wedding venue.

If we broke up, it would crush her heart and I would be seriously worried she would contemplate harming herself.

What do I do?
<bot>: My fiancé has no friends other than me and her family, and I'm too far deep to break up with her. What do I do?