<human>: Give me the gist of the text in a nutshell

My roommate "Sid" and I are both first year graduate students in the same program. We found each other via a facebook group so we aren't close but get along well. We both moved in about 2.5 weeks ago and he's from out of state. The problem is that I just got this facebook message:

>"Hi! I'm "Tara", Sid's girlfriend in (their home state). Sid's birthday is next month and I was planning on surprising him with either a visit or a care package. Sid said he'd be happy to have me visit and stay at your guys' place but I wanted to clear it with you first! I'd be quiet and respectful of any house rules you guys have and would be happy to cook for you both. If it's not okay, I understand and can find a hotel. I'd also like to send him some gift cards to local restaurants and I'm sure he'd like to take you too, so let me know what restaurants you guys like around there! As a reminder, all of this is currently secret and in the planning stage so I'd appreciate it if you didn't mention anything about this message to Sid. Thank you and hope to hear from you soon!"

I don't care if she stays with us and I'm in an LDR too so I can sympathize. BUT: Sid's never mentioned a girlfriend. We've been busy moving in and starting school but he's probably had opportunities to mention her. He met my girlfriend on skype. Our school has a big party scene and he's been going out with our program but I don't think he's hooked up with anyone. There are friendly posts from her on his facebook but no status or obvious couple pictures. I can't see her page.

Not a big deal but "Tara" knows that I'm online and saw the message. Reddit, what should I do here? I don't want to ruin our roommate relationship or invite a crazy girl to stay but I also hate cheaters.
<bot>: Roommate's girlfriend asked for permission to visit. He hasn't mentioned a girlfriend. No dead social media giveaways about him being a cheater or her being crazy.