My boyfriend and I have been dating now for nearly 3 months and he went on holiday about 2 weeks ago and he met some girl there however she fancies him and I got a little jealous and when he came back I thought he may have forgotten about her since he lives in manchester and she lives in london but then he went to shrewsbury for his birthday when she came down to manchester but before he eft she gave him his present and asked him if he wants to go down to london for a sleepover so he asked me and I was not okay with it as just about anything could happen then when I told him that, it was quite fragile between the two of us then he said he was going to sleep at his mates now he's back an he's acting weird e.g he keeps telling me he loves me, he keeps avoiding me by changing our plans etc

Maybe he's cheating... probably he's cheating... or at least he's thinking about it.

3 months you said? Tell him it's over and move on. If you're 3 months into this relationship and things are going this way already, you are likely in for a bumpy ride down the road. You are better off to end it now before you become more emotionally involved and the whole thing winds up hurting you more than it will if you end it now. Trust is obviously not there and if you are doubting him already (and personally, I think you have reason to doubt him), it's not going to get any easier, it's just going to get worse.

Good luck

Get the facts by talking to him, and seeing if you believe him, or not. If you don't, just dump him, as this is a lot of drama, and uncertainty, when you should be having fun.

Suggest, you should get the facts. Him avoiding you and acting weird, and dropping plans, and these kind of behaviors after what has happened... definitely needs to discussed. Tell him what you have in your mind, that you cannot trust him because of the way he behaves after this incident. If he fails to justify, that's where you should draw the lines.