When you confuse about halal vs haram, think like this...
From an Islamic point of view, every action you do should have a
Niyyat and a purpose.
And your comfort is not considered as purpose.
I think it is applicable to almost anything. Including music.
That means, an Islamic way of life ( Deenul Islam ) emphasizes prior knowledge of what are you going to do, why are you doing it and how are you going to do it. Doing stuff on the flow is not the way of Islam.
Prophet said: " Deeds are [a result] only of the intentions [of the actor], and an individual is [rewarded] only according to that which he intends."
when it comes to your question, There are few things odd in it.
Definitely it's not Haram to have a relationship. Unless it's kept a secret and there is no formal contract between the spouses. It's not OK to meet somebody on one day, mingle a little and sleep together and split the day after that. Every relationship is given high importance in Islam. whether it be relationship btw brothers, sisters, parents, children, neighbor, friends, teachers, students or partners. Every relationship is important. The relationship btw Spouses are even more important.
Never get into a relationship, if you doubt it might not work out.
and to the second point Purpose, does having a girlfriend have any other purpose than your comfort?
Getting to know her better. Do you really believe a lifetime is enough to understand another human being. It's a lame argument. Think about how many relationships fail after a long history of knowing each other or dating.
The important fact that Islam proposes is that be aware of your contract, aware of your limits, respect the contracts, respect each other.
And live a life for the sake of your lord. For the after life. Not this life.
And think about it, There is nothing in a person that going to stay the same for a life time, whether it be beauty, shape, sound, wealth or attitude. All of which going to change over time. Even you are going to change over time. It won't be the same person you know today 2 or 3 years later.
Love your spouse because he/she is your spouse.
There is no reason to searching reasons to love somebody.