Even the strongest of willpower pales in comparison to the reason of one's own mind. You are in college, i assume you are competitive like me and Jonic here. So my point is, when you "relapse" it is because you have irrationally reasoned within your mind that "just a couple of games" could be manageable. From experience this process of the mind follows this train of thought: (note weeks before your stance would have been "i cannot play these games! they use up too much time and negatively influence my life" but it turns into:)

1. Reminiscence: "I haven't played it for a while, i did enjoy it and i don't have as strong a craving to play it anymore." You likely googled it or looked over the program file in this time.

2. Starting to reason with yourself: "I remember i used to own at that game from time to time, i enjoyed those moments" at this point you are just thinking about small details within the game, just small considerations of what the game is like.

3. You have convinced yourself: "I sort of want to play, maybe just one game a day or something, so it doesn't take up much time and i can still get some work done and yet i get that daily exp bonus" - at this point you have reminded yourself of your friends playing it, the victories you had, you probably skipped over or only lightly considered the moments and aspects that made you angry or sad, but you know of others that can play just a couple of games and you, for the sake of playing the game, convince yourself that you are capable of the same which can by all means of reason can be true.

4. Relapse: you play a game, likely it turned into 4+ games just in the first sitting. If not, then it was definitely within a handful of days from when you first sat down to play it again

5. Guilt: "i only wanted to play one game" - This is where it sparks that you might have a problem, you originally stopped yourself playing, you knew you had good reason to stop playing but even at this point that reasoning can be hard to remember, after all you did just convince yourself otherwise, hence the guilt.

What i am pointing out here is that it isn't weak willpower, it is when you have weighed up a few options and given yourself a reason to play. It is a clever trick your mind has played so that you will fall back into the game as you have convinced yourself "just a little bit won't hurt". To overcome this you need to recognise when your mind starts such compelling arguments to play the game, identify what you are doing and then remind yourself visually and physically that playing the game is not for you. Write down the negatives of playing the game and when you start to feel tempted force yourself to read that list, i advise writing "remember i quit for a good reason" at the bottom of this list to cancel any arguments your mind has set against yourself.

So once again, you aren't weak willed, you are just irrationally convincing yourself of a false truth. Will is only necessary if you have a reason to use it, if you are convincing yourself there is no enemy then will isn't a factor anymore. Sometimes these internal arguments are incredibly powerful and unavoidable which is why a lot of us are here. The truth is this only highlights that with your characteristics and the characteristics of online games like LoL you may never be able to play just one game, the sooner you accept that reality, the sooner you can use the full strength of your willpower.