I'm jealous my roommates dog -.-

(Thats the only pic i have of him sorry)
So -_- yeah, I'm jealous of my roommates dog... Don't worry I'll explain why.
First off, I share a birthday with this damn dog. My birthday is May 31st, tomorrow. And so is this dogs. Most people would maybe give a dog some nice treats or a new toy and that would be that. But my roommates treat this dog like their kid. If she had her way shed throw a big party for this dog and invite all her friends, they spoil it to death I swear. Now this isn't the part thats making me so jealous necessarily. It is their dog after all and they can treat it however they wish and I could care less most of the time.
The thing thats really getting to me is my boyfriend and the way he has been acting towards THEIR dog since we moved in here. He gives that stupid dog a sweeter and longer good morning than he gives me.
Yesterday he told me he wanted to get THEIR DOG a present for its birthday. I was annoyed but I just said whatever and was expecting him to maybe get the dog a biscuit.
No. That wasnt his thoughts.
He wanted to buy the dog a soccerball, and a really nice one at that that would've cost $25 (mind you we have a very small income, $25 purchases we kind of have to be weary of). I got mad at him. I said "are you kidding? Nick its not even our dog its THEIRS! Stop treating it like its yours, you have no responsibility over him and spending that much on him, isn't just "being nice" its being excessive!"
Im just really frustrated that even my boyfriend is acting like this. That this dog has been taking preference over me for awhile now, and now this DOGS birthday is going to be taking preference over mine. I know this makes me sound like an attention whore, but I can promise I'm not, (not to the extent this is possibly making me sound). Its extremely annoying that a dog that my boyfriend and I don't even own is getting more attention most days already and now even on my birthday he will be too.
He really is a good and cute dog but with the way everyone around here treats him its makingg me resent the puppy more and more every day.
Im not asking for a solution to my jealousy here but am I right to be feeling this way?!