Yes, things can turn serious if it started off casual.
However, you are better off letting this person know how you feel right now instead of waiting.
When people wait for things to get serious, they exacerbate the situation.
The reason why this is not the right approach is because a casual relationship isn’t defined with anything definitive in mind.
A casual relationship is basically a relationship that is being experienced in the moment.
It is not mapped out or consistent.
It has no real bearing.
It is about how you both feel in the here and now.
The longer the casual relationship lasts, the easier it is to fall into this lackadaisical and noncommittal mode of thinking.
When this thinking gets to the point that it has become habit, it is a lot more difficult for the casual relationship to get serious.
It is just so much more challenging to break out of that mode of thinking.
One partner may eventually be willing to do so but the other isn’t.
The other isn’t because they have gotten used to the casual relationship.
After this much time, to suddenly want this person to start thinking about the relationship in a different way would be very disingenuous.
This is why it is crucial that you let this person know what you want right now.
Tell them that you are looking for a serious relationship.
By doing this, you have planted the seed.
Even if the person may be against it at this time, with some time to reflect, they may actually come to realize that they do want a serious relationship.
Sometimes this is honestly all it takes for someone to realize that they want more than they thought they did in a relationship.
That other person has to step up and be clear about the fact that they want a serious relationship.
Once one partner has stepped up, it is easier for the other to come on board.
If they are against it, they may just need some time to figure out their own feelings.
If this person gets to missing you after your reveal of what you want, they may come to realize that they actually have feelings for you.
This is why you would need to be firm about this.
Don’t just tell them that you want a serious relationship but allow the casual relationship to keep going on.
If you were to do this, the person may believe that you are not serious about what you want.
You should be steadfast in what you want.
You can’t continue the casual relationship.
You have to stop it in order to send the right message to this person.
They may try to convince you to keep going but you can’t.
You have to give them the opportunity to truly reflect on what they want.
Once they have had this time to reflect on what they want, they may come back. They may realize that they want a serious relationship as well.
However, if they don’t come back, you can move on to someone who actually wants a serious relationship.
This still bodes well for you.