if hes with someone else why was he so persistant in calling or texting me all the time

hehe yeah i thought busted at first too coz i deliberetley sent the message when i knew she was going to be around, but ive seen msgs on facebook between them they seem fine...

broke up with ex 2 months he was still at me saying he loves me and misses me and is sorry about how hes treated me about a very personal issue i won't go into..i then found out he has been seeing a much older women at work for 2 months (in her own words)..when i went to confront him about why he's saying these things if he's seeing someone he said he wasn't seeing anyone that there just friends and i did get him to admit he has feelings for her though in his reply to why he was saying these things to me he said i just said those things because i thought i was never going to see you again and had to get it out of my system i had no intention of saying them to get back together...so 2 weeks later we were still talking trying out this being friends thing...i started to send him sexual scenario messages he was puzzled and asked me why i was sending them when i had no intention of acting upon them..this went on for a few days so then i stopped and then he started doing it to me so we agreed to meet up for some fun..so deed done...i then sent him a message saying how good it was blah blah blah and he sends a message back saying dont just send **** to my phone..ive sent a few messages asking him whats wrong and why is he ignoring me now and yes still getting ignored....any ideas as to what might be going through his mind??