I love my boyfriend and summer is coming and I am scared that he is going to brake up with me like my last 2 boyfriend did because they wanted to be singale and they want to be singale for other girls don't know what to do??

Why would your boyfriend break up with you because the summer is coming?

Better opportunity.

But, if this is why he might break up with you... you don't need him as a boyfriend.

If he breaks up with you, then he's not worth your time. A guy that wants to make himself "available" doesn't really love you nor like you. If he's so willing to drop you and pick up another girl, then he doesn't care about you. Do you really need a guy that only wants you to fill up his spare time?
There's no need to do anything at all, go with the flow. Don't try to change for him nor blame yourself if he breaks up with you! You deserve better! I wish you the best of luck!