<human>: So my boyfriend and I have a red heeler mix that we adopted from our local animal shelter. 
~she is two years old
~very well behaved
~has worked up to being able to be alone in the house for about two and a half hours
~is doing well with her off leash work
~loves playing with other dogs (and hasn't met a dog she doesn't like)

I worry sometimes that she gets bored however. We take her on walks and hikes and have a big grassy area that we play ball with her at our apartment, but I think she would love a friend to play with when we're at home. My boyfriend thinks it will be too expensive to get another dog and that we should wait until we are done with school. My thing is that by the time we are done our dog will be 5 or 6 years old and I would worry that she would be too used to being an only dog and be unhappy with a new puppy. I'm wondering if r/dogs has some experience on how much more money they spend on a second dog. We both have well-paying jobs and are only going to school part time, so we have plenty of time to train the dog. We also live in Montana if that helps.

Give me a shortened version of the text
<bot>: I would like to get a friend for our only dog, boyfriend thinks it will be too expensive. Looking for some advice from r/dogs :)