Dueinmay I think you are looking at his I love you's the wrong way. I have a different more guy like take I think.
You said its not spontaneous, and that you'd much rather it be. I think you feel that it's not genuine unless it's spontaneous. This line of thinking is very troublesome since you expect him to express his love on your terms.
At the same time you seem to be down playing when he does say it. Keep this in mind when he says it at night and before departing, he is not only telling you he loves you, but double checking that you still do.
After all the stress of a long day saying I love you is a simple but effective way of reconnecting. Especially if one of his love languages is words of affirmation. Before departing it may be because he wants the strength of knowing he is loved.
At this point he needs this reassurance, and even if it does not feel genuine to you, it is probably very real to him. If anything next time he does throw him a big hug. Make him feel loved, but understand that it'll take time until he is ready to express it back in exactly the way you want.
