Guy problems

So I've been with this guy for only 1,5 months and it's been long distance. We met in Australia and bonded straight away and he's the sweetest guy ever and he started liking me a lot very fast. He kissed another girl 3 weeks ago and said he didn't remember it, I found out from my friend because they're living in the same hostel. I forgave him. Now he "passed out" on a sofa with a girl in the hostel and says nothing happened and it's not a massive deal.. I'm in Thailand atm and going home to Finland after and we are supposed to meet up in Australia again in a month. I have no idea what to do if I should just leave it but it's so hard and I like him a lot. When we are together everything is great it's just the distance between us that makes it hard. Please I need some help! Thank you! Xx