New Brunswick has a lot of college kids but I lived there when I was commuting to NYC (1hr 15 min) by train and my partner was driving to Princeton (about 30-40min by car depending on traffic, so probably a bit longer to Philly). I feel it’s more realistic/fair than both of you living in Princeton with one of you having a much shorter/better commute. Plus if your partner doesn’t want to drive they can take the train to Philly too.