*** to be a little more clear.... I love Theo and those chapters with him were so beautiful that I go back and read them again...
Theo seems, from what I read, as not a virgin.. don't know if I didn't got it right.. and she's 15...and so shy to get in the intimacy part quickly... so leaving his parts will accomplish to let it sit.. and grow.. she will get used to him.. so she can trust him... you don't need to make them a couple yet.. Just co-exist.. with little lingering glances.. built it slowly.. (please don't make him hurt her by being with other girls .. that's the only thing I can ask you... at least not him being interested or involved with others)
If you decide to remove him but keep him in the same position (who he is, his friends, "work") you automatically lose the "I just saw her and she seems like an angel in my arms" effect, which was absolutely perfect you will get it back only if you make him someone who just got there from somewhere else...
It's your book and whatever you do with it should be your choice only and not just because someone didn't like something.. you will never please everyone at once and maybe by changing your work you will lose something beautiful. Your writing is amazing, you put effort and thought in what you do ...we can see that from the time you take from chapter to chapter, you don't rush it and the results are always incredible, so have a little trust in YOUR opinion... try to please yourself and that voice in your head who makes you write your story, stay true to yourself! you've done an amazing work here to start second guessing it.