<human>: I have been dating my boyfriend (23) for a year, but I've known him for nearly 4 all up (backstory: we were very good friends before this. I liked him from the beginning. I am 21 (F), he is my first boyfriend and the only boy I ever considered dating basically). 

He's very sweet, open and honest. However, he's cheated a girlfriend in the past (him and his previous girlfriend both cheated on their partners and then began dating). From what he's told me, that relationship seemed pretty poisonous and it delayed him asking me out because he wanted to ensure he was ready to make a commitment to someone else.

In all honesty, he has given me absolutely no reason to think he is cheating, and for the most part I hardly think about it, but when I do, it's crippling, and I wonder whether he'll just change back to the way he was all of a sudden and decide he just wants to be with someone else.

Can you give me a shortened version of the text?
<bot>: Basically my question is, are my trust issues valid and or is it my own insecurities that are affecting me, given that I haven't been in a relationship before?