Alfius has already partly answered your question.
I can tell you more about what the game will be like after the rebuild and what the project will be like at the end of season 2.
As Alfius said the game is based on flirting with more girls but there is the possibility of being monogamous.
Yvette and Ashley already have their "Girlfriend routine" and the story with Michelle is moving in that direction too.
Surely if you want to totally avoid other girls you lose a lot of content because this game more than being based on "building a relationship" is based on "finding a girl to build a relationship with..."
in rebuild I'm curing, among other things, this side of the game to make more linear some storylines even with girls with which this thing was not expected. So especially when you enter the Girlfriend routine with a girl, the score of how much you frequent her weekly will be more accurate and the consequences to that score will be more important in the relationship.
All the girls who are in "Girlfriend routine" will have a weekly event that if not done will lead to problems with the relationship.
as it already happens in the current version of the game I leave a free evening to participate in this event. other possible free evenings happen if in the main storyline is planned an event that the mc has no trigger (either because he decided that a girl does not like or because he failed to trigger it)
As far as Irene is concerned, her season 2 storyline was created to make you take an important decision about her.
For her as for most of the other girls at the end of season 2 there will be two possible scenarios. (3 if you count not having a relationship with her). To put it simply: One is the result of behaving well and the other is the result of behaving badly.
(I could start a discussion about what it means to behave well or behave badly but my English would not support me).
so, yes, There's a chance that Irene will eventually be "free for a relationship and she's really interested in you", as well as Melissa, Andrea, Adele and other girls...
So the final answer is yes. it is possible to build a relationship with one of the girls but the game does not start from a relationship already built and to be maintained, the game starts from the mc who is single and knows several girls and as he can decide if some of them (or one in particular) can interest him.
A concrete example of this development can be Michelle. at the beginning the story seems to be just sex and she herself seems reluctant to have a relationship, but as you continue in the game she gets more and more attached to you.(if you behave in the right way)
sorry for the long answer, but as you can see the game is complex and I want to explian well
Thanks for the answer.
In this case, the long answer is the best answer. And this is what I needed
I am completely satisfied with the information received and I really like the direction the game is moving. Indeed, in the end, every player who is interested in this game will get what he wants.