To good to be true

I have been in a relationship with my current boyfriend for four months now and he is honestly the loveliest man I’ve ever met in my life. He makes me laugh, he brushes my hair for me, tells me I’m pretty when I look like an evil bed goblin, buys me sanitary towels and deep heat packs when I’m on my period and is just so incredibly perfect.

However, I have reservations about our relationship mainly due to an age difference. I am 23 and he is 18. I have had 3 serious relationships before and I am his first relationship and have taken his virginity (I’m the only girl he’s ever kissed). I would like for this relationship to be my last but I fear that he is too young and will want to experience variety of different partners and sexual relationships, which although makes me incredibly sad to think about I understand and respect. He however says he isn’t interested in that whatsoever and can only see his future with me. He talks about us living together and children (we both work together at a childcare setting so not as weird as it sounds) and all sorts. I am trying to hold back falling in love in fear of being hurt when I lose him.

Am I being ridiculous or sensible to hold back my emotions? I have been seriously hurt by boys before and the last boy I was with broke up with me 6 months before we were supposed to be married. I hate feeling like I’m wasting my time in a relationship that’s got no future.