I think it could be that he interpreted your message the wrong way, maybe he wanted it to be more lovey dovey if it wasn't?
He(Venus) has just squared Saturn, which implies restriction, on other hand Saturn is also your message and the square shows some obstacle and tension here with the message and him.
Also Mercury conjunct Neptune in your 3rd would show some confusion with your communiction or thinking process, could mean the message you sent was a bit confusing. Mercury is the natural ruler of communications and Neptune makes that communication a bit vague and confusing, hidden messages, need to read between lines.
So even though you might think the message was straight forward, he I believe, got confused by it....
But also judging from what you wrote about his strange past behaviour, I wouldn't be surprised that he is behaving this way now... He is just a strange guy maybe....
Sun is his 3rd, communications ruler and just recently entered Pisces, it has just left Aquarius, its detriment, so I think he will start to communicate more regularly, his overall behaviour might not change much but his back and forth communication might improve.