There are lots of reasons why a jungler hasn't ganked your lane. Here are a few:
1. You are a shitty laner. Your limited map awareness has caused you do one or more of the following when I paths towards your lane: A) You push the lane so that ganking means diving. B) You've expended all your mana and now have nothing to contribute to a gank. C) You've allowed a massive wave to build up such that the minions will kill us before we kill the enemy. D) You've already died several times or ceded so much priority to the enemy that you're no longer strong enough to contribute to a gank.
2. Winning your lane is not a win condition because: A) You're a tank. B) Your opponent is a tank. C) Another lane is a more important win condition.
3. You suck at warding. Lack of wards means I can't see ahead of time to countergank, or more importantly, that I won't be counterganked. If you have no wards and you aren't superior to your opponent enough that I'm confident we win a 2v2, I don't want to take the risk. Learn to ward.
4. The enemy jungler has targeted, most likely because of 1 and 3 above, and I don't want to fight a 2v2.
5. Your opponent is hard to gank. LeBlanc, Lissandra, Zed - basically champions that will waste my time and not reward us with a kill/assist are low priority.
6. You've shown you're not a team player. This might be A) not leashing when I ask for it because I want to path a certain way, B) not coming to help when a ward catches an incoming invade, C) not moving to an objective when I need help taking it. Or it could be something else. You know it when you see it.
7. You annoy me. You're constantly pointing out mistakes you perceive others are making, either with chat or pings. You're constantly begging for ganks. You look to blame people when things don't go our way. This is related to 6.