Well, let me start by saying that this is a tricky question to answer. All guys are different. My perspective may not be the same perspective as your man's. But there are usually clear signals that a guy will give if he is truly committed. Here are a few tips for women to help them understand if their man is in it for the long haul or just playing games:
1. Is your guy a man of his word?
One immediate, or almost immediate indicator that your man is committed to you, or that at least he's trying hard to fight for you while away, is to see if he is keeping his word. For me, keeping your word is one of the most important elements to keep harmony in a long distance relationship or in any relationship. Keeping your word builds trust and respect, and makes everything much easier, because if he says it, you know it's happening. For example, if he tells you he's going to see you on the first opportunity he has, either a vacation, a long weekend, or even a couple days from work, make sure he does it, and does not take this opportunity to go out with his friends instead. Or if he tells you he loves you, make sure he shows it, because remember, words fly as fast as the wind.
2. Is he keeping the romance or the fire on in the relationship?
Being away doesn't mean he should stop being romantic. Being away means his body is away, not his heart, not his soul, not his mind. Make sure he takes care of the little details that make you happy. I'm going to put myself as an example on this one (sorry!). As you know, or if you don't know now you'll now know; I live on a tiny (very tiny) island in the middle of nowhere. This place has a lot of challenges; slow Internet, limited courier services, telecommunication issues, etc., just to mention a few, nevertheless I always remember to send a gift on special occasions. On Easter of 2008, I sent her a big basket full of candy and other goodies. Valentine's day, I sent her a box of chocolates. One day, just because I missed her, I sent her a big stuffed animal (a monkey to be specific), so she could hold it at night, if she missed me. Not that I resemble a monkey or anything, but I figured it was a good way to keep the romance flowing and a good way for her to remember me at night, or just anytime she saw it. The point of the story is to make sure your man keeps you happy and romanced, because you deserve it!
3. Does your man ever talk about the "M" word, or at least a formal proposal?
Being on a long distance relationship requires a LOT of commitment, like we've said before, but most important is the benefit from it, after it is over. That is why it is very important for your man to talk about your future together. Does he talk about marriage or about proposing or anything as such? If he doesn't then you should ask yourself why. There must be a reason why he wants to continue with a relationship while away. Just make sure he's not playing with you and just having you to cover his solitude. If your man talks about the next step, he is committed. If he doesn't, ask him why not, and discuss it with him. There's nothing better than a good discussion about your future with him. It'll give you a good indicator of what he's up to. Just make sure you don't pressure him, otherwise he can feel threatened (you know how men are!). Just have an open and honest discussion about it, see the pros and cons, and you'll open a channel of communication that will be very rewarding.
Long distance relationships are challenging by nature, and like I said before, they require a lot of commitment, so if you and your man had a discussion about in advance, and went for it, I can almost reassure you that he is committed enough. It's just the little things that keep the glow on the relationship (from both sides). The key is to always talk about how you feel and be open to accept things and change things if necessary. Remember: "Comitttment is the path to success"