Average fart volume per day is 476 - 1,491mL/24h, so let's take 745,5 mL/24h as average, which gives us 272.107,5 mL a year, or 272,10 Liters a year.

Let's say a third of this is expelled while at home, so 204,07 L a year. Suppose your gf farts in front of you half the time, that gives 102,03 L.

Basically, you breathe in about a hundred liters of her farts straight into your lungs a year. If you took it all at once, you would probably die from hydrogen sulfide poisoning or at least get eye damage or a pulmonary edema.