Okay so she's bored with the relationship, and sex is practically nonexistent now. You could try and ramp up your sex life with some new ideas / kink, but if she's bored with the relationship that's pretty hard to heal without time and radical changes, including your vacancy from her (absence makes the heart grow fonder).
Unfortunately, I also stupidly have not been keeping up my social skills or flirting with girls during the relationship, so I will be completely destroyed by an open relationship where she is the only one able to do stuff.
Yea if it's a one sided open relationship that sounds like an emotional storm.
I recommend you do what you can to try and fix this as fast is possible. It may take some time, but you need these skills for developing satisfying relationships (girlfriend or not).
Would it be better to say no to her open relationship proposal and stick it out to the end of senior year but possibly risk cheating?
should I just decline her open relationship proposal and wait it out for the lease at the end of school year?
Try and think about what you're asking here. Relationships are two sided. You don't have control over whether or not she has deemed the relationship "over with" internally. Whether or not you're "boyfriend and girlfriend" as one might put it, the reality of the relationship dynamic wouldn't reflect the title.
would it be better to just say yes to the proposal? would it be better to somehow ask her what would happen to our housing situation if we broke up?
Okay, some of the things I say here may come across as hurtful, but I say them only to bring light to some possible realities.
Things were fine in terms of getting along and emotionally.
Is there a difference between your two's relationship and a relationship you might have with a platonic roommate, other than the title of boyfriend and girlfriend? If so, what?
Personally, I would speculate that she probably is using the open relationship card as a way to bend out of her reality of "I'm stuck living with a guy that I'm in a subsided relationship with, but he's my boyfriend."
If that's the case, these are the options I see:
Yes
You could say, yes, that sounds like a good idea. Then, you could start working on your social skills and seduction abilities and get good enough to bring home new girls, and still have your original girl to have a relationship with. You only have a year left of school anyways, why not go fishing for some pussy? Probably gonna be a weird storm of good and bad emotions from that, and you're definitely working with some unorthodox relationship dynamics living together.
You could say yes, and then only commit to her while she fucks other dudes. Obviously this would be bad for anyone emotionally.
With either one of those options, you're gonna have to deal with the reality of her fucking other dudes.
OR
No
You could say no, we're staying boyfriend and girlfriend. This is like strangling the relationship though, which sucks the life out of it even more, don't you think? Her proposing an open relationship is her saying "I think we should see other people". If you could build rapid attraction in a second, that might fix that, but that takes time bro, especially if she's known you for 4 years, she probably has a good idea in her head of who she thinks you are.
You could say no, this relationship is over. Find someone to sublease for you, or for her, and have one of you move out.
You could also say no, this relationship is over, and not move out. Then you'd have to live with eachother through all the awkward moments and possible emotional turmoil of seeing one another move into things with different people.
There may be more there, but that's what seems plausible to me.
Bottom Line
Work on your social skills and fundamentals.
Try and think of what she wants too.
Try to put emotions aside for the housing situation, and reach a logical conclusion from both ends.
It's ultimately your decision to make, and what's important to you.
I hope this helps, and wish best of luck to you bruddah.