My best friend kissed me and now is avoiding me

So we have been best friends for years, we always go out together and are constantly in each other’s company. Every now and then he says that I’m the only woman in the world he would want to have a relationship with. We text each other all the time. He has said “I love you” a number of times. But nothing had actually happened between us. Then this last year we had a bad fight and stayed apart for a couple of months.

So about a month ago, he called me and asked me out for dinner, said this whole situation was terrible and if I could forgive him, which I did. We started seeing each other again. Since then, I noticed that he was looking at me differently. He started buying me gifts all the time. We would sit opposite each other at the restaurant and he would keep looking at me and say things like, “your skin is perfect” or “you’re so beautiful”. At the beach he would keep looking me up and down. He would put his hand on my leg while he was driving, which he had never done before. Then one night we had dinner at this fancy restaurant and he kissed me for the first time. It was lovely, and I really think he enjoyed it. That was about a month ago.

The next day, it got weird. He became a different person out of nowhere. He stopped texting me on Whatsapp, which he used to do all the time. When I asked him if something was wrong, he said he was very busy with his thesis, “we will see each other soon”. We did go out once after that for dinner, but it was really awkward. During the first hour or so, he barely talked except to answer a question I asked. He didn’t even look at me while he was talking, he kept saying that he was tired, that he needed to sleep early. Normally he would take me to his place after dinner so I could play with the cats and we would stay together a little longer, but this time he said he would take me home directly. He kissed me on the cheek, or rather, kissed the air, instead of hugging me and then holding my hand like he normally does. And he didn’t get in touch again since then.

I know he IS actually busy, as he does have an exam in a few days, but I have seen him on Facebook a lot, commenting on people’s photos, and he has been chatting with other people without problems (we have several friends in common, so I know). Apparently, he’s not that busy, and just avoiding me.

Why? If we had met a couple of weeks ago I could understand, but I’m his best friend in the world. If I text him, he answers, but it’s always rushed and mentioning how busy he is, that he is going to sleep, that he’s tired, that he can’t talk right now, that he’s running errands. It just got really weird. Why is he ignoring me?