Something isn’t working between you and your boyfriend. I’ve been in your position before, and if you’re getting those feelings, then you’re most probably unhappy with your current partner. I’m married to a stunning woman who I love, and I wouldn’t even look in another woman’s direction with any interest because everything’s great (in the bedroom too). Equally, I can’t imagine being with somebody and knowing - even though he doesn’t - that she was getting a kick from the idea of being with another person.

You said you don’t want to break up, so you need to figure out whether that’s because you actually see a future with this guy or because you like being in a relationship. If it’s the latter, we’ll, you’ll get that security and sense of belonging in other relationships too when you’re with the right person. If it’s the former, then .. well, to be honest, it’s probably not. Not if you’re entertaining the idea of an affair. Maybe, subconsciously, you’re not ready to commit to one person? There’s nothing wrong with that; you’re 18.

Disclaimer: No judgement :)