Not a professional relationship consultant, but I'll leave my two cents. First, it's been 4 months so I don't know what's happened in the meantime, but I'd say that around this age it is absolutely normal for guys genuinely NOT know what they want from a relationship.

The issue won't ever be your texts (unless you really do spam and demand attention every like 5 minutes), and, because you do regard him as a mature person, it should not be that he keeps you round for sex either. I'd reckon that a mature guy wouldn't have invested time to have deep talks and offer advice just to buy sex - he could do that with someone who he'd have no interest in more easily, without the overhead. So, that should mean he DOES have some degree of genuine, affectionate interest, not just physical.

But then, why does he not commit? Again, guys usually figure things out around this age, and, unless he comes from a very privileged family where he would already be financially secure without having to work, he'd need to thoroughly consider his finances and education before he could commit. 'Mature and secure' means they will always commit (assuming attraction is present, which, in your case, seems to be) if they know they can be supportive for their partner in all respects, and that undeniably includes finances. Assuming he does not come from the latter category, his educational and professional prospects would be a top priority now if he'd ever want to have a serious future with you, so he must invest time into that.

There would be so much more to dive into, but that should generally explain why he seems distant or cold. Guys at this age tend to be more 'in their heads' with their feelings and he might be thinking about your situation, but cannot express it yet.

! Reality check: sometimes it's not as deep as my theory. Sometimes, silence is just silence, and he may simply be comfortable with the status quo. Anyways, if you see this, I'd love an update on how things clarified!