I respectfully beg to differ, puzzleannie. Being a boyfriend and girlfriend is not a sexual partnership, in that you are right. However, it is a form of partnership of life, as it is a commitment based on romantic love, which is looking at engagement and further at marriage, at least in some hopeful and putative way. I suppose the term “lovers” as it was used before it acquired a sexual meaning, could be used. As such, it is possible to cheat on a boyfriend or girlfriend, although it does not mean he or she has any rights to our body (I wouldn’t be so sure about his or her not having any rights to our person, though again - even engagement doesn’t give any action). An obligation to fidelity does exist in such nascent relationships and the moment fidelity is implied, it is an offence against the person to breach that fidelity - and it’s not only the same generic offence as generally breaking a promise or betraying trust. This is part of the reason why romantic relationships shouldn’t be entered into lightly.
Additionally, as the “romantic stuff” exists not for a fun time together but for discerning vocation and finding a partner for marriage, having a boyfriend or girlfriend is no mere social activity. In so far as it were to be a mere social activity, one should simply not have boyfriends or girlfriends. It’s not like it’s all fine so long as no sex is there (there exist acts which do not cause sexual arousal but at the same time do not belong amongst expressions of friendship but rather of romantic love, and those acts are not there for our own amusement or freely exchanging with friends for our gratification - therefore while merely socialising with other friends is surely not cheating, there is certainly something between friendly socialising and sexual acts - and that something is not to be taken lightly or discounted) - it all has a clear and ordered purpose with a place in God’s plan of life and even His plan of salvation - as marriage is ordered to lead to salvation and having a boyfriend or girlfriend is anciliary to marriage as the ultimate purpose.
For reasons given above, I must insist that a boyfriend or a girlfriend is not a light matter and that it’s also possible to cheat on such a person. I don’t expect you altogether to disagree with me, so please don’t take my post as a sign of total defiance. The distinction between marriage and lack of it is huge indeed, but I needed to speak up for what I did.
As for the Opening Poster:
I cheated on my boyfriend and I told him and we broke up. I have repented. Is it possible to make one forgive me?
No, it is not possible to make someone forgive us and if it were possible to force forgiveness, it would be worth nothing. Please understand that lack of forgiveness from someone on whom you have committed a sin (if you have) does not hold you down. The absolution for whatever acts you’re talking about is or will be valid regardless of forgiveness from other people.
Following what puzzleannie said, please see things in the correct perspective. If what you did was a sexual act (I’m not asking and I’d rather you wouldn’t say), the offence is that of fornication. It’s an offence that consists in having sex with a person to whom you are not married, not an offence consisting in violating some bond of fidelity with your boyfriend. Fornication is the primary matter here. While just because the sixth commandment talks about wives and husbands doesn’t mean that cheating in premarital romantic relationships is fine (and the first three paragraphs of what I wrote say why), the primary problem is having sex with a person to whom one is not married, since sex does not belong in romantic relationships before marriage.