Search Results: asking a girl out to lunch

We've been talking for about 6 months now-- a lot of emotional and intellectual intimacy. Yes, we've also slept together, but only a few times so this isn't necessarily about that. We message each other every day (before work, during our lunch break, and after work we talk for a few hours). In any case, anytime I bring up wanting more-- he says it isn't possible. He says he likes me and there is a connection between us but since I'm currently in grad school and his job is unstable, it just doesn't make sense. He acts like I'm asking to get married-- I only want some level of commitment so I don't feel like I'm wasting my time-- but he claims that would be unfair to me, especially when he can't promise me anything right now. The thing is-- every time I say I can't do this anymore and need to leave-- he won't let me leave. He'll somehow convince me to stay or message me saying he misses me, etc. I don't understand. What exactly is he getting out of this? He's very experienced and could get any girl he wanted-- why put so much effort on me?