On my birthday I went to a club and kissed someone

Well at the moment you have done well by realising you are in the wrong and now you want to change :) He is gunna feel a bit betrayed and you are gunna have to build that trust back up with him again. 1. talk to him normally and build your friendship up. 2. arange for you and your mates and him and his mates to go out in a group some where :) (that will also build up your friendship) 3. send him texts or call him just to keep up to date with him. 4. When he is breaking up with her of vice versa be there for him to comfort him and tell him you will nver leave his side. 5. When he isnt going out wiv his girlfriend any more send flirty texts and tell him you miss him and how much he means to you. you can also say to him “I took what I had for granted, and didnt really realise how much it meaned to me until it was gone” – sorry it was long lol hope this helps good luck :)