TL;DR: My girlfriend and I have been talking about opening the relationship. She wants to start with threesomes with other girls, but I'm pushing for fully open eventually. I'm high SMV and I don't like how much pussy I turn down, but the relationship is wonderful and I don't want to sacrifice that. How do I maintain the relationship while fucking other girls?

I'm attractive. 25, 6'4, 200 lbs and getting bigger every day (I would be getting a lot bigger but I can't financially commit to a cycle yet), and very handsome although I look young. I'm smart, kind, I like joking around but I don't put up with BS. I'm working on upping my game around people I don't know; I was awkward and shy in high school and these days I can afford to skate by on my looks for the most part so I still choke up sometimes. The biggest blow to my SMV is probably that I'm a wageslave server, so I work a lot but I don't have money to go out very often.

My gf is attractive, but she's put on some weight since we got together. She's counting calories and exercising now but progress is slow. I love her, we have a lease together, she contributes more financially than I do, and the relationship is generally great. Few shit tests, few of any arguments, the sex is frequent and incredible... I'm not leaving her, not for a long while. However, our SMVs were close when we first got together but lately I'm quite a bit higher than her. If we were to open the relationship, I could easily find more attractive women than her. I've already been turning them down. She would not find more attractive men than me.

I'm looking for a redpill take on how to keep my gf happy while bringing other women into the bedroom, and potentially opening it up later on. What should I expect, avoid, etc. Anyone with experience or advice, please weigh in. If we do go the way of open... how should I handle her exploits with other guys? I'm not really jealous but I don't want to lose her respect or dedication.

EDIT: To be clear, I'm mostly worried about her getting jealous of other girls and then trying to use her fuckbuddies to lash out at me and make me want to end it with others, rather than her leaving me. If either of us were interested in settling down, I think this would be more of an issue. But we have VERY similar short term (-2 years) goals that mean staying together makes our lives a LOT easier, and our long term goals (2+ years) both include selling everything and leaving the state if not the country. So the only real improvement she could make over me would be a guy who could pay for more things, and she would find that whether we were in an open relationship or not.