Send an email asking your manager how they're doing, what interesting things are happening, and how you can help them with what they're doing. One short paragraph. No negative thoughts. No "hurt and licking my wounds" undertone. No "you've been ignoring me" or "I feel excluded". Just something with the general feeling of "hey, how are you holding up, hope you're doing fine, how may I help".
They may have forgotten about you. They may not be checking with you because your performance ratings are high and you don't require to be "managed" that much, and their attention is on someone who's having trouble performing their job. Heck, they may be having trouble or going through harsh times. You don't know.
I have seen this very dynamic happen when I was in contact with both the "boss" and the "contributor" who felt the "boss" was mad at them and shunning them and didn't want to talk with them but I had first hand factual knowlege that none of this was true. I gave the same remark as the above. The "boss" was happy to receive the email, and the contributor was relieved to find out that all their thoughts were unfounded.
Now, I'm not telling you that your boss is not ignoring you; that is a possibility, after all. I'm telling you that there's a high chance it's not the case.
You are a seasoned contributor and it's not lost on you that managing your manager is something you ought to do.
>My guess is that, he wants to promote his favorites and he wants me to leave on my own. How do I handle this situation?
>I know that the most common advice would be, speak to him. I am not considering it. Because it might turn out to be a false alarm I would be assigned a module which I am not interested in.
This is a dangerous vicious circle: assuming the manager has bad intentions, being aware of the most common advice, which is the most common for a reason, and not wanting to speak with the manager.
You'll go into overdrive for nothing as the work life balance is very good, and your performance is high. You will waste this.