Hi Everyone,
Thank you for all of your help.
As an update, I arrived at Heathrow January 8, 2012 and made it into the UK.
I brought an organized folder with me, complete with letters from my US employers saying I've been granted a leave of absence for my time in the UK, along with recent pay stubs from both. I also brought a letter from my girlfriend stating our relationship and the fact that she'd be providing accommodation for me during my visit, along with a copy of her main passport page. I also brought bank statements from all of my accounts proving I had sufficient funds ($30,000US) to support myself until May. In addition, I also brought proof of weddings I plan on attending in May and June, proof of insurance for my stay and printouts of Paragraph 41.
When I approached the IO, she looked at the card I filled out on the plane and asked some questions - purpose of visit (visiting my girlfriend), what I do at home (on leave of absence) and length of stay (nearly 4 months). She questioned me about my relationship with my girlfriend (how we met, how long we've been together, what she's studying, how long until she graduates, etc). She reviewed both letters from my employers which stated I'm expected to return to work during the second week of May, in addition to glancing at my bank statements.
After reviewing the letters and asking some questions about the jobs and my return to them, in addition to asking about my planned stay (what I'd be doing, won't I be bored, money I have access to, accommodation), the IO went on to explain that she was going to grant me entry to the UK; however, she was going to put a special stamp in my passport stating the length I was allowed to stay (six months) along with something like a case number. She said that the case number would caution IO's in the future that I'd visited for an extended period and they could look up information I'd given her during this talk in the future. She said that if I planned on returning to the UK any time in the next year, to expect to be questioned heavily by the IO since 4 months is long enough to "start a life in the UK" and that IO's in the future will be "suspicious". After the explanation, she stamped my passport and I was through Border Control!
All is well here. I'm in the UK for another month and a week. As of now, I don't have plans to return in the next 3-5 months, but I fully plan on bringing the same sort of paperwork with me next time I visit in case of any suspicion.
Thank you everyone for all your help, and I hope this update helps other people with similar questions/concerns in the future.
