This manga honestly comes as a surprise. The title of the manga is so-so and honestly, they never truly tie the knot even to the end. At most it's about a guy taking great interest in a half t-rex upper body human female. So, the whole "girlfriend" thing is pretty false. He never asks her out and she never shows any clear romantic interest in him either, honestly I don't really feel like what he feels is truly romantic either but rather interest and possession, like with a pet, but it's heartwarming anyway. To call it "Everyday life with an airheaded T-Rex" would be much more fitting and describe this.
So, basically the setting is that dinosaurs never went extinct and every single one of them evolved to have a human shaped upper body to "avoid extinction", pretty silly but it works. The protagonist, a random dude with balls of steel, takes an interest in an airheaded t-rex girl with no clothes on, huge chest, penchant for digging through the garbage and a mind that appears to tilt slightly towards the more feral rather than human side and also enjoys things like scaring people.
The protagonist enters the stage and starts paying a lot of attention to her, gradually getting closer and more personal, though never to the point of any real romance. It truly feels like the relationship between a fairly stupid pet and its owner teasing it and taking care of it while enduring all the weird stuff she does. The dino setting makes for a lot of pretty amusing situations and actions that would be abnormal for a human but probably wouldn't be for a dinosaur.
It's chill, easy to read and amusing enough. I liked it. A great part is that the author knew just where to stop, at the end of volume 2 was probably where the setting started to lose its appeal, you can only juice something like this that is good because it's unique for so long before it gets a bit stale. 3 Volumes would've been pushing it, 4 would've been too much and by 5 I would've either quickly flipped through it or dropped it, so ending it at volume 2 was great.
If there was anything I have to complain about, it's that their relationship really hardly have any substantial progress. While they get closer, it's as I said before just similar to getting closer as a master and super sized, super powered yet stupid pet. Maybe some build up with a short and simple confession, them officially becoming a couple and perhaps showing something fun like an afterstory of their relationship a few years into the future. But lacking that, it ends up falling a bit flat, especially with how the title promised a real romantic relationship, but they never even get into a superficial couple relationship. A bit of a bummer and why I really feel like the title should've been different along with some parts of it, such as if he always treated her like a pet-like existence to take care of, it would've been better. Let's not talk about the morality of such a relationship when almost all girls in this story are literally oversized lizards with a human upper body stuck to it.
Oh, and I would never call this a shoujo manga so I highly disagree with whoever added that. While the author is female and clearly has some works that are made to appeal mainly towards female audiences, this one is definitely neutral. Neither the art style nor dialogue really betrayed anything that made it feel off as a male, it reminds me of many different shounen manga. I tend to be sensitive to actual shoujo/josei manga and hate reading them, so I believe others will probably agree that this isn't particularly geared towards girls.