You should investigate whether he is not being loving or interested, or if he’s just not doing that in the way that you expect or are used to. You may have unspoken expectations or fantasies of what a relationship should look like, and your projections are getting in the way of appreciating the good relationship you actually have. It sounds like you might have different love languages as well, where you need a lot of verbal affirmation and maybe that’s not his strong suit. That is something you can discuss with him and ask for more of. You can tell him what’s working for you and what’s not, or that you’re unsure whether he’s into you romantically despite all the evidence, and try to hear and understand where he is coming from.
Another frequent error is wanting to talk constantly about the past in your messages. You have to stop focusing on your nostalgia and on what you’ve experienced together. You ex needs something else. It’s of course tempting to send a little message saying, “I miss you,” “I love you,” or “My feelings for you are still strong.” Truth be told, during this stage these types of things can damage your odds of success so refrain from sending them.