I only eat lunch and part of dinner, sometimes I fully eat dinner sometimes I don't. all this has been triggered due to the loss of my relationship with my girlfriend who I love with all my heart. I mean I shouldn't be complaining I was kinda overweight but now its like wow. I dropped almost 4 inches on my waist size, in a few weeks, is this normal or am I going to collapse?

No, it is not normal or healthy. You are experiencing weight loss due to depression. When you regain your normal perspective on life you will, most likely, gain it back. Get out a bit more and find out why your relationship ended. This will help you gain a better attitude towards your life. I don't think you will collapse. If you feel that the weight loss is actually good for you than write down what you are eating and how much so that when you feel better you can eat the same things and will continue to lose weight until you get to a good weight for you. You also might try exercising more as that will release more endorphins which will make you feel even better.

you could be ill losing too much weight quickly is bad and can cause heart problems espically if you have an eating disorder

no go to your doctor you could have diabetes or something or you are pining to much over your loved one.

You should know that you are lose weight that you are missing your ex-girlfriend, to see whether to date her again or not. You thinking of her everyminutes. How can you get the mood in having meal or drinking.
George, You are a smart kid! Once you decided to give both end a spacing, you should insist to the commit as there will have a real love on the date of commitments. Everything take in Natal that what you see and think will be beautifully.