When an ex text you

So I started seeing this guy about 3 months ago it got too serious too fast but 3 weeks ago he dumped me out of the blue. I heard his back with his ex now and I haven’t talked to him for two weeks. He message me last night (Valentine’s Day) asking what’s up. I didn’t reply and left him on read. What does he want 🤔 it’s not a big deal really but I’m just curious of what he wants, shouldn’t he be with he’s girl? Anyone have any good advice? 😌