2k rentals will chafe the Mustachian impulses... but in your grand scheme of things, if your jobs are stable, it's barely a speed bump. You don't sound like you want to commit to the house, and both parties should really be completely on board for that money-hose.
As for the apartment, sacking sub-15k of progress when you're making almost 100k (less taxes?) for the 'stache is going to slow you down only a little. It's ok to wonder if this is an article of happiness for her, or an impulse to keep up with the Joneses, but only your communication can give you a better bead on that. Even if she buys a pile of expensive furniture, it's a few more months. If she really wants to be the magnanimous hostess, it's easy to give her the opportunity to start in an apartment. It will scratch the hosting itch without necessarily expanding into an executive dining room and a new deck. It will offer the opportunity to try a different, expanded homeowner arrangement and see how you both like it, without risking a short-term purchase of a house.
There are as many upgrades as you can imagine for a house; as Malkynn pointed out, far fewer for an apartment. If it's insufficient, it will still be better for a year or two, and by then you'll be comfortably close to retirement and can revisit the house idea. You can even turn this into a money-, time-, and life-saving compromise if you can get an apartment significantly closer to work, given those long commutes, and the real cost may be much lower than you think.