Why does not he end this?

Guys, me nd my boyfriend are in relation from 7 months.. there were a lot of fights in beginning but love on both sides was present.. because of my harsh past where I have badly cheated by my ex i was unable to trust my recent boyfriend completely.. i always used to insecure and always had doubts that whether my boyfriend will cheat me like my ex did.. though that was not my mistake but I have suffered a lot in my past.. no matter what my boyfriend never left me he always made me understand that nothing was like that.. in these 7 months I couldn't stop overthinking nd being insecure.. nd this result in making my boyfriend tensed depressed...
I was also feeling the same as there was lack of understanding.. he used to put all the blame on me.. that relation was falling just because of me.. though we both tried to make this work.. I changed myself to better extent.. but till my boyfriend got tired of this shit.. he asked me for space for first time.. I gave him nd he made it clear that it was not a breakup he just need time for himself.. after space I contacted him but though he was not talking like before.. I thought I should finish this relation as I couldn't make him more depressed but yet he is not leaving me.. i told him that this relation is getting toxic. but he said he never thought of ending it nd will never do... I can't understand he is so much stressed but then why dont he leave me?
Why does not he end this?
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