'euphoria experienced by youths during a first love can make it more difficult to find happiness with a future partner'

 I agree with this statement as if their first love ended badly, or if they broke up, all the happiness and all the excitement that they feel will be stuck in their head and in the future, when finding a new partner, they will be afraid of whether they will feel the same hurt that they felt when they broke up and will also have higher expectations for their next partner too.causing it to be hard to find their parthner with a higher expectation.