I don't think you understand the plot. The main girl is the only female love interest.
There is no harem. The reason why is because:
1. Tiltu (the young ancient dragon girl) is a young girl who is too overpowered and thus is an outcast among her kind. She is too young to understand love and romance in the proper way. (Her being an outcast for a long time didn't help this.)
She's using the marriage excuse to create a connection with him so that she could be loved, cared for and accepted. This is what she really wants. The MC treats her like a clingy little sister that needs comforting.
2. None of the females in rotation (the main people show up in a rotation apparently) have any romantic desires for the MC. He's just treated like a neighbor and friend. Nothing more, nothing less.
3. In order for a manga to gain the harem title, the 3 requirements you need to have are:
A. Romance
B. 3 or more mainstay girls( background or one chapter girls don't count)
C. At least 3 females who have romantic desires for the MC
This manga does not satisfy requirement C and thus is not a harem manga.
4. It takes a while but eventually the MC and the Main girl start having these romance atmosphere moments regularly. He even later has a vision that shows the Main girl holding his future child.
If you're going to say stuff, as least be factually accurate.
Ok I hear you, this might not be an actual harem, but I'm pretty sure it is still a pseudo harem / soft harem. Which is a harem with no romance required. Perhaps not all the females in rotation have romantic feelings for the mc, but it doesn't take away from my point of the writing being shallow.
The young dragon girl using marriage as an excuse to stick to the mc already shows the mentality of the author while writing this. Out of all the possible excuses, the author chose marriage, and they didn't make mc strongly reject or at least be decently taken aback at the remark. He should be sitting her down to teach her boundaries or the correct relationship they should have.
If it really were just an excuse to create a connection, why couldn't the author just make the dragon girl want to be MC's sister? It just screams p*dophillia, or at least the misogynistic notion that these girls should depend on another male in such a manner, and only then can they get the love they deserve.
Same goes for the other girls. They may have their own "problems" and their own "personalities", but if you look deeper and really look at the writing, these girls all exist to orbit around the protagonist, whether they are supporting, depending or validating him for his actions. Their personalities are thinner than paper, and there's only the mildly interesting plot background info that holds these characters up. Just slap a few lines of how this character suffered and we are done, right? My point is this makes them feel decorative and very fanservice-y.
On a technicality I might be wrong, but can you really say that the plot you speak of hold true with the characters' actions? Like the plot is that the magician girl is one of the strongest magicians, but is she acting like one? Can you blame me for calling it a harem with how poorly these female characters are being written? Ive read real harems with better written female characters than this. Was the story so good for you to want to start nitpicking on my usage of the word harem on a story that clearly has some sort of harem going on?
So yeah I'll take back my comment on how there should be a harem tag, but you really had to come
Wow this is bad. Mc is just entirely covered with plot armour, whose only mission is to protect his girls and only troubles is his magician girl/comrades getting in danger. Neither his personality nor his OP abilities are remotely interesting.
Also, 4 chapters in and already 3 women. The magician girl is the peak of characters only added for fan service. From the "mouth to mouth resuscitation" and the stripping of clothes.
And Magician girl keeps collapsing from "intense magical energy emitted" by others or sth, but after collapsing she becomes completely fine with interacting with them afterwards, it is clearly just a show for the author to keep readers reading.
She has been saved by mc 3-4 times already for goodness sake, the epitome of damsel in distress. "One of the strongest magicians" but of course having zero ability to defend herself when mc is around.
Overall plot is not plotting and feels like it's made to be a money grabber by the author. Also needs a harem tag.