Is being "scared of [one's] feelings" a real thing, or just an excuse?

In a dating context, if one person is being somewhat distant and hard to read, there are usually two explanations that are offered: (1) the person is just not that interested, or (2) the person is interested, but has been hurt in the past and is scared of getting involved.

I am wondering if (2) is bullshit. People get hurt all the time, and rebound into relationships that end up being successful, or just deal with their pain and manage to act like normal human beings.

I am dating someone who ended a 12 year long relationship about 6 months ago. We have had many conversations about it and agreed to proceed slowly and with caution, and to just date casually for a little while.

About two months in, we had a long conversation and agreed that we were comfortable making it a little more serious, and considering it a full relationship.

This was last week, and I feel like I have been getting very confusing mixed signals since then. We were both out of town for the holiday weekend, and I barely heard from him the whole time, which gave me an uneasy feeling. The day we got home, he said he was tired and didn’t want to get together, and he had plans for the following night also, so I haven’t seen him since.

My friends say he is probably scared and doesn’t want to get hurt again. I think that sounds like an excuse and probably means he just doesn’t like me. Either way, I worry this means I need to just abandon this relationship, and I was hoping to get some (gentle, please) feedback either way. I am crazy about him and would love to make it work, but I don’t know if I’m just deluding myself.