What do you call someone who desperately needs (or better said craves) everyone to like them?

Solution 1:

I think the most obvious choice would be needy itself:

needy adj
2. Wanting or needing affection, attention, or reassurance, especially to an excessive degree.

TFD

Note that in AmE you will frequently hear the term "high maintenance" ("My girlfriend/boyfriend is so high maintenance!") used as a synonym for needy. Whereas needy has an alternate meaning that refers to someone who is merely poor or disadvantaged, high maintenance has nothing associated with it that absolves its target from blame.

Solution 2:

If you want a more pejorative term, in the US, you would call him an

attention whore

a more polite version of this is

attention hog

If they tend to seek approval by trying to please everyone, then you could use

sycophant

noun

a person who acts obsequiously toward someone important in order to gain advantage. (Google)

or its synonyms:

yes-man, bootlicker, brown-noser, toady, lickspittle, flatterer, flunky, lackey, spaniel, doormat, stooge, cringer, suck, suck-up (Google)

Solution 3:

Your friend wants to be a cynosure.

TFD defines cynosure as a person or thing that attracts notice, esp because of its brilliance or beauty.

Your friend may or may not attract every person, but he definitely strives to be one.