Mariana, please don't fall into the trap of assigning motives to your son ('he can't be bothered'). Unless he's said that this is the reason, you just don't know. There may be anything going on that he doesn't want to talk about, and he is not obliged to tell you everything - plus, it may be something to do with his gf. I'm not going to start coming up with scenarios, but if he has always been happy to visit before, the odds are that 'can't be bothered' is not on the list of possibles.
Mu mum assumed that I was frightened of flying because we never went on package holidays. I'm not, and never was. I have flown a lot. There was a (private) reason for not going at the time, but she told the whole family and friends that Doodle was scared of flying. When I found out I was furious, but she just shrugged, and said 'What am I supposed to do if you don't tell me? I had to assume.' IMO what she was supposed to do was MHOB, as it had nothing to do with her.
Not the same thing, I know, as this does affect you, but the point is that you don't know what's going on in other people's lives - even those of your children.