I'll play the devil's advocate. Charges are:
- "Railroading into plot", by burning house/garden (arson!) and sending a masked ass... pestering, annoyance of an NPC.
- Protecting DM's wife.
- Making wife's PC a central one (plot and character's development, no disadvantages, her attacks do lasting damage)
- Knocking out highest DEF char with a single punch.
- Ignoring the stats.
- Outshine PC by NPC. In cold blood.
- Being a roommate...?
Railroading: quite appropriate if party agreed on "we want to be thrown into plot fast and not bother with team building but we don't have a team concept so do it for us DM".
Protecting significant other and making her central: if she's new to RPG and was hesitant, it might have been her condition for playing. Or him being nice to her. Or both. Or "no sex if I look bad" was used. Motivation here can be key if you wish to change the situation. Or even react appropriately (roommate etc.).
Or perhaps whole campaign was devised with one character at the center. Then said character dying can screw things royally.
Knocking highest DEF char with a single punch: if a seemingly innocent NPC who's actually rather sinister came along, taking on best equipped fighter is a given, serves as a good warning to rest of the team. Yes, it can be done better, but when improvising people don't always go for best. Oh no, they turned left! Quickly!
Ignoring the stats: easy to counter. There's this DM with 6 year's experience, can't he say "I'm sorry, but how did that happen, if my character has a sneak attack?"
Outshine PC by NPC. In cold blood: serious joy-killer. Record all examples and then approach the DM and say: here, here, here and here and here, and also there. In all those situations my PC was completely useless. I get it that she doesn't have but I dislike it. I mean: I want less of those situations and more of those... whom I couldn't record because not a single one happened: when my PC stole the limelight and was awesome because . Something like did with that attack. Or the other thing. Or that yet another thing.
Being a roommate...: sorry, but I'll ask bluntly (I don't know how to do it better). Is there some other tension over unwashed dishes or bad hygiene or WHATEVER between you? You don't need to answer me / us / here. Just answer this yourself, if you want to approach this in civilised manner. If you are repressing yourself over something else AND his DMing, both will come out when you unbottle just one - all it takes is a moment of anger.
And some serious questions:
is your wording by chance or are you trying to convey deeper meaning? Is wife, fiancee, roommate relevant here or could it equally well be "DM, player A, player B, DM's girl"? In other words: pairs competing for instance? Again, I don't need to know the answer - you do.
Your fiancée was solicited for feedback - ain't this a good sign? When was it? How long ago? Implementing feedback overnight ain't easy, are you guys helping the DM with it?
have you talked this over with ANYBODY in the team? Those "two other friends", who are not part of any pairing here, are they with you on this? Or perhaps they said "it's between you guys, we don't have troubles with his DMing"?