He is at a point in his relationship with you where he realizes that he is falling for you, and sees a future with you.

Being that you have been seeing each other for a decent amount of time now, this isn’t unusual.

He sees you as someone that he wants to be in a long-term serious relationship with.

As a result, he keeps apologizing for no reason to you, worried about jeopardizing his relationship with you.

At the outset of the relationship, his mindset was different.

You were getting to know each other and there were no real stakes.

He found you attractive and wanted to see where this new and exciting relationship would lead.

Now that a good amount of time has elapsed since the onset of the relationship, his mindset around how he feels about you has evolved.

He knows that he wants to keep you around.

He has gotten to know you a lot better in this time frame, and believes that he has developed a strong romantic connection with you.

As a result, he has gone from not having any emotional stakes in the relationship to having them.

He knows that this is a relationship he values greatly, and would be unhappy about losing.

This is a guy that keeps apologizing for no reason on account of his emotional investment in you, and a fear of not wanting to mess up the relationship.

This is where he keeps apologizing whenever he deems he has said or done something that would turn you off.

He doesn’t want to take the risk of losing you over anything that he says or does.

Ergo, he is careful with what he says and does.

He isn’t entirely certain about how you feel about him emotionally, as he doesn’t know whether you are feeling likewise about him.

To play it safe, he keeps apologizing for what seems to you as no justifiable reason, so that you never get the feeling that he doesn’t have your best interests at heart.

This is new to him.

He is used to girls showing interest in him initially, and that interest fizzling out over a short period of time.

This has been his dating history, and what he is accustomed to.

Basically, he isn’t used to having a girl stick around this far into courtship.

Unfortunately, he has had a history of messing up somewhere along the way as he is courting a girl, and turning her off.

She consequently lets him go.

Being that you are still around, he isn’t experienced enough to know how to act to keep the relationship going.

As a consequence, his only avenue is to apologize for no reason.

By doing this, he hopes to soften you up so that you never dwell on anything that he deems would turn you off.

Girls have left him in the past for facetious reasons, and he is now overcorrecting by apologizing for no reason so that you stick around.